I finished my Mainline build. I did the resistance and voltage checks, plugged it in to my Schiit Bifrost Uber and it worked without issue! It's completely stock other than the paint and wood varnish which you can see from my previous post earlier in this forum (reposted below). I did no parts burn in before the build, so my first impressions are all on listening to the amp within hours of powering it up for the first time. I have a Schiit Lyr (hybrid tube / solid state) and Schiit Valhalla (all tube OTL) to compare to, both with many hours of listening and high end NOS tubes from the 60's and 70's. I plugged everything in and listened to high res audio from my Mac through USB to the Schiit Bifrost Uber.
First off, my impressions are that the Mainline sounds AMAZING with all my headphones: AKG K1000, Audeze LCD-2.2 (non Fazor), Hifiman HE-500, Sennhiser HD 650, Beyerdynamic DT770 600 ohm (with LCD cable mod), AKG K553 Pro, Audio Technica ATH-m50.
Overall, when compared to my two other amps the Mainline EASILY bests them. An interesting observation is that when I listen to each of my cans through the two Schiit amps, I can distinctly hear the differences between the headphones. On the Lyr the LCD-2.2 is the leader, but the HE-500 is also good with diminishing returns on HD 650, DT770 on down the line with the K1K sounding the worst. The Valhalla favors the HD 650 and DT770 with the K1K sounding better than on the Lyr so long as you don't mind having little or no bass. The LCD sound OK, and the HE-500, K553, and m50 all don't work well with it.
The Mainline on the other hand, made every headphone I own sound noticeably better and the differences between the headphones on the Mainline narrowed. Said another way, each headphone sounds so much better on the Mainline that they all sound really great and starts to level the playing field of the cans. That isn't to say that it makes every headphone sound the same. There are differences, but just not as dramatic as on the other two amps. It doesn't favor low impedance cans vs. high impedance cans. For example I can't listen to the HE-500 on the Valhalla because it is way too murky and the bass just flabby and horrible.
I'll go through each headphone and give my impressions in order of my preference. K1K is only at the top because of my excitement to have a headphone amp that can finally drive them well.
AKG K1000
I know Doc B has publicly stated that the Mainline wasn't intended to drive the K1K, however based on the headphone amps I have it is the clear winner by a long shot. The Lyr has enough power to drive the K1K, but I find that it is too crisp and analytic. The bass is decent on the Lyr, but the high end is so sharp that I can't listen for long without feeling like I can't take it anymore, not more than several tracks. The Valhalla with K1K is more smooth but it has almost no bass, one of the main criticisms of the K1K. The Mainline smooths the treble out on the K1K and delivers the most bass that I've heard out of them. I could listen for hours without feeling fatigue and the Mainline really draws out the mids. Vocals sound so real and the overall sound stage is otherworldly (the strength of K1K) so much that I truly feel like music is being performed in the room for me. I do have to crank the volume to near max, but it gets plenty loud on all recordings without distortion or noise floor. Just in case people don't know, the K1K comes standard with a non-removable balanced cable. I listened in balanced mode with the Mainline set to high impedance.
Audeze LCD-2.2 (non Fazor)
So far my favorite pairing. My favorite setup prior to Mainline with LCD was my Lyr and a pair of 60s Amperex Orange Globe tubes. The Mainline brings out so much more in the LCD, the bass is stronger and more tight but not overly strong, just a great attack and decay. The mids and treble are more smooth and the sound stage opens up even more than on the Lyr. I listened with a balanced cable in balanced mode and the Mainline set to high impedance, interestingly enough. The sound stage opened just a tad more on high impedance and the bass had a touch more power. The Valhalla does a decent job with the LCD, but wow, the Mainline has so much more of everything in comparison.
Hifiman HE-500
Very close in sound to the LCDs but with slightly less sound stage, slightly brighter highs, and a little less bass. Used a balanced cable and listened in balanced mode on the Mainline. With HE-500, the impedance switch didn't make much of a difference in the sound. Also the Mainline didn't improve on the sound quality as much over the Lyr as with other cans. In comparison, the Lyr likes the HE-500 and does a really great job with them, probably due to the power output. If I didn't have the LCDs to compare with, I'd love these cans with both the Lyr and the Mainline. But when compared to the improved sound stage and wonderful bass of the LCD, they get beaten out. HE-500 with the Valhalla sounds awful. The bass is, well... sad.
Sennheiser HD-650
I thought the Mainline was going to have a hard time besting the Valhalla with some ealy 70's Russian tubes I have for it. The bass on the Mainline is improved, stronger and more tight. The mids and sound stage open up a little more than on the Valhalla. And I feel like I hear more details. The only complaint is that I start to hear what people call the 650 veil on the Mainline. It's almost as if the sound is so smooth it starts to feel too soft. Maybe it's the treble in the very high register doesn't quite match the mid and low end. I only have a single ended cable so I didn't listen in balanced mode and switching to high impedance was clearly better on the Mainline. The Valhalla on the 650 is a great pairing, but again the Mainline outshines. If you're OK with the smoother sound and slight veil, then this is a superb pairing. I didn't get to jazz, but I believe this match would excel with jazz. Lyr does a fine job with 650, but no comparison to Valhalla or Mainline.
Beyerdynamic DT770 600 ohm
WHOA the bass! I thought the bass was strong with the Valhalla but Mainline just thundered with these cans and not in a bad way. It sounded good and tight, not rumbly or flabby in any way. Of course with closed cans the sound stage can't compare with open cans but pretty darn good for . But the sound quality and details in the treble and mids are fantastic. I have modded my DT770 to work with an Audeze LCD balanced cable (same Tiny XLR jacks as LCD), so I listened in balanced mode and switched to high impedance. Again the 770 with Valhalla was a great paring, but the Mainline brings so much power and clarity to these cans, that they win the award for most improved. If you don't like strong bass then this wouldn't be a paring for you. The Lyr also does a decent job with the 770 but it is beaten by Valhalla and walloped by Mainline.
AKG K553 Pro
I know it's a little ridiculous to pair a $130 (Massdrop price) pair of headphones with a $1200 amp (not including cost to build bringing it to more like $2K+), but I bought them for portable use so I thought I'd try them out with the Mainline. They sound
really good with the Mainline. The're not overly bright as some people have stated on the K553 head-fi forum. For closed cans they beat the DT770 in sound stage. Theres a little upper mid range crackling on lower volume levels. The bass is good, not as strong as the DT770 (which is mind blowingly powerful) and slightly flabby. The Mainline makes these cans sound like headphones on par with DT770 at 1/2 the cost and brings them close to HD 650 at 1/3 the cost. These are also not broken in with only around 10 hours of use since new. Listening in single ended and low impedance modes on the Mainline. When compared to the Lyr, the bass is better. On the Lyr the bass is very bloomy and mids are not as crisp and clear. The treble on the Lyr seems to work well with the K553, but really these sound like average cans with the Lyr whereas the Mainline brings out a lot in the quality of sound.
Audio Techica ATH-m50
These are my previous portable phones that are now replaced by the K553s. A great set of headphones and also not up to par for the Mainline. Once again though the Mainline brings out the best of these cans. The bass is a touch bloomy like the sound of the K553 with the Lyr. The mids and sound stage are pretty good though. Like the K553 I am listening on single ended and low impedance settings. On the Lyr as a comparison these cans really don't sound particularly special. I am hearing some slight crunchyness in the upper mids and the bass again is bloomy and loose. The mid range is rather thin and flabby and there is no sound stage at all. Going back to the Mainline, they sound much bigger and more detailed, especially meaty in the mid range.
AIAIAI TMA-1
"Oh where did these come from?" you ask. I threw them in for S&G. I actually don't think of these as serious headphones because I use them as a phone headset. On the Mainline, single ended and low impedance, they are seriously veiled. Almost a wash of mid range with very little crisp upper end and not a whole lot of deep rich bass. Yep, leave them as a phone headset...
I played around a lot with balanced vs. unbalanced and the impedance switch. For the high impedance cans: K1K, DT770, and HD 650, the high impedance setting is a must in terms of opening up sound stage and tightening up bass. The high impedance setting also improved the LCDs in the same way, but not as severe. The HE-500 and lower impedance cans didn't seem to make a difference which setting the impedance switch was on. Balanced mode and balanced cables gave the cans a little more gain, but didn't seem to change the quality or characteristic of sound in any way.
I have to say, I'm extremely happy with this amp. It was a joy to build and in the end I have my end game headphone amp that seems to drive everything I can throw at it. The only headphone that I imagine a purpose built amp could benefit from is the AKG K1000. All my other headphones excel when driven by the Mainline. At this point I'm seriously considering selling the Lyr and the HE-500. The Mainline is far superior than the Lyr in every aspect. The Valhalla can do a really great job wtih the HD 650 and DT770 600 ohm, so I'll keep that for office listening. Same story with the HE-500. The Mainline plus LCD is just that much more everything. So there's no use for an another planar magnetic that is so similar. My favorite setup that I'll be doing a lot of listening on is the LCD 2.2 with the Mainline. What a match! With all the rave reviews of HD 800 and Mainline, I'm super tempted!
-Robert
