Bottlehead Mainline DIY Amplifier

The Bottlehead Mainline is the top of the line DIY headphone amplifier in Bottlehead’s range. Unlike other products in the Bottlehead range, the Mainline doesn’t have any “standard” upgrade options like the Crack‘s Speedball or the S.E.X.‘s C4S kit so the review that follows represents the stock Mainline kit which is also the peak version of the Mainline without getting into aftermarket, non-standard modifications.

The Mainline kit costs USD $1199 before shipping and represents a significant price jump over the S.E.X. and Mainline kits. This review will help you decide if it’s worth the extra clams…

The Build

As with all Bottlehead kits, the Mainline comes in pieces for you to assemble and solder yourself and that’s what makes it such a great option for Head-Fi enthusiasts – you get to pay less (because it’s a kit) and you get to build it yourself for the satisfaction and understanding that comes along with it.

Parts & Assembly

As you’d expect for the top of the line kit from Bottlehead, it’s also the most intensive in terms of parts and overall size. The box isn’t much bigger than the S.E.X. carton, but it’s jam-packed with components including chassis plate, power transformer, output transformers, switches, sockets, capacitors, diodes, more resistors than you can poke a stick at, and a bunch of different hook-up cable including single core, 2 core with drain wire, and even some Cat-5 for good measure.

It was only when I unwrapped the parcels shown on the right that I realised how many pieces made up this beast. And, by the way, the Mainline kit doesn’t come with a fiancee like the one in the picture – you’ll have to get one of those elsewhere.

 Custom Appearance

 If you’ve read my S.E.X. review, you’ll know that I like to customise my Bottlehead kits. You don’t have to do anything if you don’t want to and you can just build it straight from the box, but the beauty of receiving a kit in pieces like this is you have the opportunity to individually treat / paint / modify the parts before assembly. Doc B recommends always treating the bell end (the cover for the power transformer) to prevent superficial rust, but that’s the only recommended pre-assembly work if you don’t feel the need to customise.

My custom treatment saw me once again return to Jimmy at Riga Craft in Cheltenham in Melbourne. Jimmy did an amazing job on the chassis plate of the S.E.X. and I hoped he could repeat the performance on the Mainline plate.

This type of work is not what Riga normally do and the Mainline proved more challenging for some reason. Jimmy did great work and made multiple attempts to get the chassis plate just right, but eventually had to concede that the plate would never be 100% blemish free. He was extremely helpful and the final product is a reflection of the challenges of anodising an item like this, not a reflection on Jimmy’s professionalism and effort. That said, the finished product was a beautiful looking blue anodised finish with the tiniest of blemishes in 2-3 spots. Only 1 blemish would be visible in the final, assembled amplifier (see top chassis image to the right) so I decided to go with a chrome pin-stripe to cover it and also add a little bit of detailing to the finished kit.

All-in-all I was really happy with the finished look of the pin-stripe and it covered the tiny blemish perfectly so if you’re thinking of anodising or painting your chassis plate, be prepared to improvise and get creative with things like pin-stripes because there is always a chance of minor blemishes in unfortunate locations no matter how careful you are.

Other than the chassis plate, I kept the rest of the customisation pretty simple with aluminium coloured engine enamel on the bell end and valve covers and a simple, linseed oil treatment on the wood base. I won’t post images here because you’ll get a chance to see it later in this review.

Hook-Up & Soldering

Much like the other Bottlehead kits, the Mainline doesn’t require an engineering degree to build and is just a matter of following the instructions carefully and taking your time.

Stage 1 is the attachment of all the components to the chassis plate. This stage is very straight-forward and possibly easier than the S.E.X. because you don’t have the top-and-bottom mounting of the chokes and transformers like you do on the S.E.X. You need to pay attention to the mounting of the tube sockets and switches to ensure the correct orientations, and there’s a little bit of adjustment to the gain switches before you install them, but that’s about as tricky as it gets.

Once assembly is done, the soldering of wires is much the same as the S.E.X. Bottlehead provide multi-core cables for the signal and power so there are less individual strands going all over the place. This keeps the process nice and neat, but means stripping and prepping multi-core cables which can be a little fiddly so there’s a trade-off. For what it’s worth, I like the end result with the neatness of the Cat-5 and 2-core cables so it’s worth the minor hassle of stripping multiple layers of insulation.

Another part of assembly is the “building” of the attenuators. At the bottom of the image of the un-wired chassis above right, you will see two blue circles with multiple silver terminals. These are the gain switches and require the installation of a series of resistors between the switch terminals and the terminal strips on either side.

I was initially intimidated by this step, but can report that it’s quite manageable (with care and attention) thanks to the always excellent instructions provided by Bottlehead. I managed to goof on one of the solder joints in this section which caused a channel imbalance on one particular gain setting, but after wasting some people’s time over on the Bottlehead Forum (thanks guys and sorry!) I discovered a solder joint had formed a void around the resistor lead. 2-3 seconds of heat from the iron and it was right as rain!

Circuit Boards

The Mainline’s power is very tightly regulated. The signal tubes are each provided with a C4S board (similar to the S.E.X. C4S upgrade), the power supply has its own circuit board featuring an array of capacitors and diodes (see image to the right), and there is a board with some trim pots to ensure that the power delivered to signal tubes is perfectly matched.

At first, I expected the circuit boards to make the Mainline more challenging to build, but in many ways it actually made the process easier because some of the tricky connections from the S.E.X. kit (e.g. the diodes on the power transformer) are addressed with much simpler circuit board assembly and then fly leads from the circuit boards to the relevant terminals on the tube sockets or transformer.

I did make one crucial error at this stage though…

When wiring the blue trim pots on the regulator board (bottom left of image to the right), I mis-understood the instructions and failed to look at the provided picture in the manual. This resulted in one terminal on each side of the circuit board being left out of the circuit and was a complete pain in the **** to fix. As always, the key with these kits is patience, care and double-checking before soldering. I failed on this occasion, but was thankfully able to fix the problem without any broken parts.

The Finished Build

Here’s a quick “fly-by” of the finished Mainline circuit to show you how it looks and how well-spaced and laid-out it is:

Top Building Tips

Much like the tips for the S.E.X. build, the Mainline is mostly about taking your time, being careful and double-checking the instructions before finalising a solder joint. Cable paths are much more defined on the Mainline so you don’t need to think ahead about where to run each cable – Bottlehead have already done that for you and even provide cable tie-down points as part of the kit and instructions.

One tip that is a bit unique here though is to do your numbering of the terminals with a fine-tip marker. The marker I usually use is a bit thick and I had trouble marking some of the tighter spots (such as the tube socket terminals) and this came back to bite me later when I soldered a capacitor to the wrong terminals and had to re-do the connections.

Design

The Mainline employs a design with output transformers so it will pair with a wider range of headphones than something like the Crack (which is output transformer-less or OTL). It also has balanced and single-ended outputs which differentiates it from the S.E.X. which is single-ended only (via the standard headphone jack). To achieve the balanced output, the Mainline has a full-sized Neutrik 4-pin XLR socket in addition to a 6mm Neutrik locking headphone jack.

It’s worth noting here that there is a switch to select between balanced and unbalanced operation and although sound comes through both outputs in either mode, the sound definitely changes when when switched correctly for the socket and ‘phones you’re using.

Another design element unique to the Mainline (in relation to the Crack and S.E.X.) is its use of attenuation switches rather than a volume knob. Front and slightly left-of-centre on the amp are 2 black knobs labelled “coarse” and “fine”. To set the volume on the Mainline, you first adjust the coarse attenuation which jumps in 9dB steps (from 0dB to -45dB) and then tweak the exact volume using the fine adjustment which moves in 1.5dB steps (from 0dB to -7.5dB).

I don’t think this approach is necessarily better in terms of usability compared to the simple volume pot, but it’s been implemented for the quality of the signal path and it works really nicely. Of course there’s no way I can compare the quality of the sound with this setup versus a traditional potentiometer so we’ll have to take Doc’s word for it, but I’m yet to be disappointed with any of Bottlehead’s design choices so I think it’s a safe bet that this is the best option they could create.

Compatibility

The Mainline has 2 different output impedances to suit high and low impedance headphones. There is a switch to select the mode you require and throwing this switch sends the signal through a different winding on the output transformer to provide more grunt to high impedance headphones, but at the cost of a higher output impedance. This makes the high output mode perfect for 300+ ohm Sennheisers and Beyerdynamics, but I’d stick to the low impedance mode for pretty much everything else just to ensure good synergy and frequency response.

Listening with the Beyerdynamic T1s I definitely notice a slightly looser bass response on the high impedance setting, but it brings a desirable warmth and fullness rather than getting sloppy and loose. Flicking back to low impedance tightens up the bass, but sounds leaner as a result. Both settings sound excellent on the 600 ohm Beyers, but not so much on my 120 ohm Fischer FA-011 LEs where the lower output is a better match, hence my recommendation of saving the high impedance mode for 300+ ohm headphones.

So far I’ve tried the Mainline with everything from 600 ohm Beyer T1s right down to 15.9 ohm Unique Melody Miracles. Normally, tube amps and desktop headphone amps aren’t great with sensitive IEMs, but the Mainline performed far better than I expected with only the faintest hum. The sound was excellent, but I think the output impedance is a little too high even on the low impedance setting to make the Mainline a good match with 16 ohm headphones or earphones and that’s completely fine with me because this is a headphone amplifier designed for high-end headphones, not hyper-sensitive IEMs or low impedance headphones designed for portable use. It’s got plenty of power for everything I’ve tried it with and it pairs extremely well with all sorts of headphones without any noise problems or impedance mismatches.

Balanced Output

Having a balanced output means the Mainline can play nicely with balanced headphones (i.e. headphones provided with balanced connections or with aftermarket cables / modification). Some common headphones that can be run balanced are Sennheisers and Beyerdynamics with dual cable entry (cable goes to both cups) and aftermarket cables / modifications, as well as the HiFiMan HE series and the Audeze LCD headphones.

Switching between balanced and unbalanced on the Mainline makes only a subtle difference to the sound with I think a slight (~1dB) volume increase running balanced and perhaps a slight increase in resolution and control. It’s not a dramatic change and I wouldn’t recommend spending a fortune for balanced headphones to go with the Mainline, but it’s definitely a nice addition if you already have balanced headphones and I love being able to have 2 sets of headphones connected – Beyer T1s and Fischer FA-011 LEs for now.

There was a bit of discussion on the thread over at Head-Fi about the fact that the Mainline has a balanced output, but only single-ended inputs. According to the discussions, this decision was made based on experiences that a good single-ended input is as good (or maybe even better) than balanced inputs due to the extra complications of input transformers for balanced inputs. Unfortunately there’s no way for me to confirm that because there’s no fully balanced Mainline that I can compare directly with, but given Doc’s track record I think it’s safe to assume that it’s a sound decision (pun slightly intended).

Tubes

The Mainline has 3 tubes in total. A 12AU7 is used to control the power while two 6C45-Pi tubes take care of the signal. From what I can tell there are really no alternatives to the 6C45 tubes other than different brand variants (some of which are getting hard to come by it seems) and there’s no point rolling the 12AU7 power tube because it doesn’t influence the sound (I’ve tried).

This means that the Mainline, like the S.E.X. is a great amp if you don’t want to fiddle around with rolling tubes, but may not be for you if you crave the opportunity to play with different tubes for their different sound characteristics. The Crack is the best (i.e. only) option for tube rolling in the Bottlehead range.

Sound

The part that really matters…

I said after installing the C4S in the S.E.X. that I was worried how good the Mainline might be if it was any kind of significant upgrade over the S.E.X. + C4S combo which is outstanding. The good news is that the Mainline didn’t blow my mind as I feared it might after hearing the S.E.X. + C4S. The bad news is that the leap from the S.E.X. to the Mainline isn’t as dramatic as I thought it might be, but don’t be discouraged – it’s worth reading more to fully understand what differentiates the Mainline from it’s cheaper brethren.

Treble

Clean, crisp, extended and detailed, but oh so polite.

The Mainline delivers smooth, but fully extended treble without a hint of hash or grain. There’s no lack of detail or clarity, but a complete lack of harshness and fatigue. The Mainline’s treble presentation is the best I’ve heard as yet in my headphone journey. Cymbals, percussion and high frequency textures are present and clean with good weight and presence, but are well-balanced with the rest of the sonic picture. Music can still be sibilant, but only as a result of a poor recording, not because of the amplifier. As strange as it sounds, that’s a good thing because it means the amp isn’t adding harshness or edge to good recordings, but while also not smoothing over poor recordings – it’s presenting what’s there in a really polite, but accurate way.

Mids

The mids from the Mainline are simply sublime. There’s a weight and substance to the mids that is reminiscent of the Crack at its best, but significantly better.

Of all the Mainline’s sonic traits, the midrange is probably the defining factor to my ears and it’s the weight of notes which signifies the difference. Instruments and vocals sound and feel real. I had never really noticed before that other amps of mine create a really enjoyable facsimile of the instruments in the recording. The reason I had never noticed is because I hadn’t heard it done just right. Hearing the Mainline has redefined my expectation of midrange presentation from an amplifier. There’s no thickness or creaminess to the midrange sounds, just a solidity and presence that’s beguiling and magical.

I wondered for a while if I’d just hit a sweet spot on certain tracks, but listening to a range of tracks showed that the Mainline excels on a range of instruments, male and female vocals, transient sounds (such as drum hits) and sustained notes – everything just sounds so real.

Bass

I’ve stated previously that the one short-coming of the S.E.X. in my eyes was its slightly lean bass presentation. I’m pleased to report that the Mainline strikes a perfect balance between the Crack and the S.E.X. It’s tighter than the Crack, but fuller than the S.E.X.

Similar to the mids, the bass from the Mainline is weighty and realistic. There is plenty of presence at the bottom end, but no bloat or bleed from the bass. As I mentioned earlier, the impedance switch can tighten or loosen the bass presentation slightly depending on your headphones, but on either setting (given appropriate impedance headphones) the bass is excellent – full, punchy, and quick with great impact, incredibly realistic weight, and just the right speed of decay.

There’s not a lot more to say about the bass of the Mainline – it just does what it should – presents the bass in a realistic way that’s accurate to the recording. There’s no emphasis or alteration that I can hear – just clean, accurate bass that’s perfectly balanced with the rest of the audio spectrum.

Staging & Imaging

If I had to choose one area that the Mainline has failed to meet my expectations, it’s in the area of stage size, but this needs some explanation…

The Mainline’s stage is more intimate than the S.E.X.’s and I simply adore the space and size you hear when plugged into the S.E.X. The Mainline’s presentation is more intimate than the S.E.X. – once again about halfway between the presentation of the Crack and the S.E.X. If the Crack is a front row seat and the S.E.X. is a 10th row seat, then the Mainline is probably a 3rd or 4th row seat. I’ll discuss the differences between the Mainline and the S.E.X. in the comparison section below.

The Mainline’s staging is open and defined despite the more intimate placement of the music so it’s not like the staging and imaging is poor, it’s just not in line with my personal preferences. That said, I’m not sure that the incredible realism and weight I discussed earlier would be possible with the more distant presentation of something like the S.E.X. and I wouldn’t trade that level of realism for anything in the world.

You might be worried that a more intimate presentation equates to a congested or crowded sound – well don’t be! Sounds are clearly separated and defined and the weight of notes discussed earlier make the imaging some of the most accurate and realistic I’ve heard. While only moderate in forward projection of the sound, the Mainline’s stage is wide and has good height.

Perhaps the strongest aspect of the Mainline’s staging and imaging is its ability to separate different sounds while maintaining a single overall auditory picture. This amp manages to keep a perfectly coherent representation of the musicians while also perfectly defining each sound in its own space. You can hear every instrument, vocal, noise and texture on its own and yet also simultaneously as a part of the overall sonic tapestry. Sounds pop out of the recording when they’re meant to and blend in when they’re meant to, but at any time you can single out any individual sound or instrument and hear it completely on it’s own without negative influence from other sounds in the recording. This all makes for an incredibly engaging listening experience and it’s got me really wanting to try the Mainline with some HD800s to see what it’s really capable of when it comes to staging and imaging. (Edit: since originally writing this review I have now bought a pair of HD800s and will comment on the pairing at the end of this review)

Sound Summary

The Mainline’s sound is effortless. It’s controlled, polite and completely coherent. At first listen you may not be “wowed” by this amp, but on extended listening you soon realise that every track you hear sounds as solid and real as you’ve ever heard it. Nothing jumps out to amaze you, but everything sounds excellent.

I used to work for Bang & Olufsen and one of the key traits with their audio and video gear was an attention to lifelike reproduction. At first, lifelike reproduction sounds ordinary and everyday – it’s only as you spend more and more time with it that your appreciation of it grows. It’s completely believable and never fatiguing because nothing is overdone or enhanced. The Mainline reminds me a lot of this approach to audio – nothing is emphasised or highlighted so it’s not an instantly exciting sound, but it’s a real sound and that continues to be enjoyable for hours on end and days, months and years of listening.

The sound of the Mainline is accurate, clean, smooth and controlled. It’s incredibly balanced across all frequencies and it delivers the same auditory experience on every track I’ve tried across all kinds of genres. This is an amp you buy to listen to and enjoy for the long haul, not to “wow” you or amaze you in the short term. The realism of sound from this amp is still enlightening me as I continue to listen – it’s a subtle kind of marvelous that has to be lived with for a while to fully understand, but it’s addictive and amazing once it starts to sink in.

Comparisons to Crack (w Speedball) and S.E.X. (w C4S)

I’ve compared the Crack and S.E.X. comprehensively in the S.E.X. review so I’m going to keep this fairly simple with descriptive explanations of how the 3 amps compare on certain traits. If you have any specific questions I’ll be happy to respond in the comments.

Signatures

The Mainline’s signature is most like the Crack w Speedball. It’s smoother than the S.E.X. with a little less treble energy, but no less detail or extension and the Mainline’s bass is a notch or two stronger than the S.E.X. Flicking between the S.E.X. and the Mainline, I’d say the the Mainline has flatter bass response while the S.E.X. sounds like it has a slight mid-bass hump before rolling off in the lower registers. This is all really subtle stuff because they all sound great, but the Mainline is clearly the most neutral / balanced sounding of all the range across all frequency ranges.

Staging & Imaging

As I’ve already mentioned, the S.E.X. presents a wider, more spacious soundstage that I just love! The Mainline’s staging is much more similar to the Crack – intimate but with more space around the sounds. For stage size alone, the S.E.X. actually wins this battle for me, but others might prefer the more intimate presentation of the Mainline.

In terms of imaging, I’d say the Mainline is easily the most realistic amp I’ve ever heard because of the weight of notes – everything sounds so real and present that it’s a revelation. The S.E.X. is excellent in terms of imaging, but sounds like an excellent reproduction while the Mainline sounds like the real thing. The Crack is commendable for its price tag (running with the stock tubes), but can’t compete with the other two in this area.

Resolution and Detail

I was expecting this to be really close, but it wasn’t… The S.E.X. produces excellent details, but the Mainline just flat-out outperforms it from a couple of perspectives. Firstly, the smoother presentation means that nothing is overshadowed. Listening to the S.E.X. I occasionally lost details behind a little bit of excess treble energy, but the Mainline never does this – everything is beautifully balanced so you can hear everything in the recording. In addition to the smooth presentation, the weight of notes from the Mainline means that even subtle details are given presence in the recording. They don’t over-step their place in the sonic landscape, but they are 100% there and you hear them all exactly how they were intended.

Reality Check

Just like I did for the S.E.X. / Crack comparison, I upgraded the tubes in the Crack to see how close I could get it to the Mainline. In its stock form, the Crack can’t compete with the Mainline (and nor should it at 30% of the price), but how about with a $20-30 12AU7 and a $150 6AS7G (brown base GEC)?

Good news in all directions! The Mainline remains clearly better in terms of refinement, space between sounds, overall stage size, and resolution. However, the $600-700 version of the Crack (i.e. price of the Crack kit + C4S + upgraded tubes) offers astounding performance for those who prefer a more intimate presentation than the S.E.X., but don’t want to go so far as the Mainline in terms of price.

The Crack remains an astounding achievement in terms of price-to-performance ratio and it’s the only Bottlehead amp to provide the fun option of tube rolling to tune the sound.

Overall Summary of the Mainline

Overall, the Mainline clearly holds its place as the flagship Bottlehead amp and is currently the best amplifier I have ever heard. The fact that you can build it yourself, customise its appearance, run balanced and unbalanced headphones, select between 2 inputs on the fly, and adjust output impedance to suit different cans makes this an outstanding amplifier for those looking for an end-game flagship amp.

On first listen I was worried that the Mainline wasn’t worth its price tag, but its real value is in how transparent and subtle it is – don’t buy the Mainline to wow your friends with a short listen, buy the Mainline to amaze yourself for months upon days upon hours of listening.

Cap Upgrade Update

Over the past few weeks (April-May 2014) I’ve installed two sets of capacitors into the Mainline starting with a set of 18uF Auricap High Resolution capacitors in the position of the stock Dayton 10uF capacitors and a set of 0.1uF FT-3 teflon capacitors fresh from Romania replacing the stock 0.1uF Daytons on the Bias Regulator board.

FT-3 Teflons – 0.1uF 600V

I’m going to start this update with the teflons on the regulator board. I’ve literally just finished this installation and it may require some time for burn-in of the teflon caps, but I honestly can’t hear any noticeable difference in the sound and would question the value given that the installation is a bit ugly and clunky due to the size of these capacitors. As you can see in the image to the right, I’ve had to run fly leads from the teflon caps which are cable tied to the Auricaps. I’ve also use some heat shrink tape to create an insulating buffer to keep the teflon caps sitting a little way off the Auricaps (even though there should be no issue with them touching due to the plastic coating on the Auricaps.

These FT-3s cost around $10 per pair plus postage (via eBay) so it’s a small enough investment that I really don’t mind if they have done absolutely nothing to the sound because they haven’t taken anything away and if they provide improvements after burn-in then that’s great.

I found some variation in the bias settings (adjustments to ensure identical voltages for each output tube) following the install so if you do change the regulator caps be sure to double-check the biasing if you want to maximise performance.

Auricap High Resolution Polypropylene – 18uF 400V

These have been in place for a few weeks now and are definitely a worthy upgrade. They cost me about $130 for the pair from a local supplier and are the best $130 I’ve spent in a while. As you can see in the pictures, they just fit in the space between the C4S boards and the output transformers, but still need a tie down using an adhesive anchor on the chassis (the same as the ones supplied with the Mainline kit to tie down the Cat 6 cables).

Having read the review of the Mainline, you’ll know that the treble on the Mainline in stock form is extended and detailed, but still smooth and non-fatiguing. I did say in the original review that there’s no hint of fatigue when listening to the Mainline, but I have to call myself a liar now and say that there must have been the tiniest hint of harshness / graininess there. I know that because now it’s gone and its absence has left all of the Mainlines magic on full display. Don’t get me wrong, the stock Mainline kit is in no way flawed. In fact, as I see it, the ability to spend $130 and 15 minutes to bring the amp to another level shows just how good this circuit is.

The sound with the Auricaps is basically identical to the overall sound of the stock Mainline only smoother, more defined and just better. Treble is smoother while still fully extended and detailed. Midrange textures are sophisticated and intricate, and the bass is extended, textured and punchy. As I said above, the best thing about the Auricaps in the Mainline is that they don’t change a great thing. They keep the Mainline’s signature and neutrality completely intact and just let it do what it does better. It’s hard to say exactly how much influence the Auricaps have had on this next part, but I would swear that the Mainline now has a clearer, stronger image than before. This is most likely due to the slightly smoother treble allowing all the other auditory cues to arrive cleanly and accurately, but the staging and imaging now with the Beyer T1s is really magical. It was good before – outstanding even, but it definitely seems even better to these ears now. I am having “wow” moments multiple times each day.

One other note as to why I chose the 18uF rather than a direct replacement of the 10uF stock caps. From the reading I did, a larger capacitance can provide better bass response which I was keen to explore to see if there was any room for improvement in the case of the Mainline. However, if there’s an improvement there I can’t tell. The hardest challenge here is that you can’t quickly A/B a capacitor change like this so it’s all based on auditory memory and the difference in bass extension (if there is one) is small enough to be insignificant, unlike the change in sophistication and smoothness in the mids and treble which is slight, but obvious.

Capacitor Wrap

The only other caps in the circuit that could potentially benefit from upgrading are the electrolytics used on the power supply board, but they fit so neatly on the board and are already good quality Panasonic capacitors so the potential benefits here seem questionable (although I’m always open to being convinced otherwise).

If I were asked today what to upgrade in the Mainline, I would strongly urge building the stock kit first and then considering the Auricaps if you like the stock sound, but I definitely think there’s huge value in hearing the stock kit first so you know which way to tweak (or not tweak) the sound if you choose to upgrade the output (technically parafeed coupling) caps. Unless something changes in the coming days / weeks in which case I’ll be back to edit this post, I wouldn’t really recommend changing the regulator caps. Keep the build neat and simple.

Sennheiser HD800 Update

Bottlehead MainlineI was recently fortunate enough to get my hands on a pair of Sennheiser HD800s (review coming soon) and the pairing with the Mainline is nothing short of perfect.

I’d heard the HD800s many times before and could never love them because of their slightly forward and sometimes analytical presentation, but the pairing with the Mainline has proved to me that the HD800s are all about the amplifier they’re paired with and they reward you handsomely when paired with the Mainline.

The Mainline offers the perfect balance of detail, intimacy, and smoothness for the HD800s to really shine. Indeed, the the Matrix X-Sabre DAC feeding the Mainline I might have just reach audio nirvana! I won’t get into a full breakdown of the HD800’s sound here, but suffice to say that with this pairing the bass is solid, but neutral and extends very deep while the mids and treble are super clean and revealing as you’d expect. The treble is slightly forward, but completely enjoyable and never “bites”. I’ve actually found myself listening at a lower level with the HD800s compared to the Beyerdynamic T1s because everything is so balanced that it sounds great at any volume.

A lot of people with HD800s have applied the well-discussed Anax mod (discussed and detailed here on Innerfidelity), but I honestly feel no need for it at all with the chain I’m using (PC via SilverPlus USB to Matrix X-Sabre to Mainline to HD800s). I can only imagine how good it will sound when I add a balanced cable for the HD800s to the mix.

So, in summary, if you have (or want) a pair of HD800s and you need an amplifier to get the most out of them, definitely add the Mainline to your list!

Lachlan Fennen Written by:

Facilitator, training design consultant, blogger / writer and amateur photographer

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