Modded M-stage version1 and Schiit Asgard comparison, [YMMV]:
Using a Marantz CD5001 and Marantz CD5003 cd players, Audioquest Black Mamba and Signal Cable Silver Resolution interconnects, AKG K702 and Sennheiser HD600 headphones, I have extensively compared the Schiit Asgard and my modified Matrix M-stage V1 with Class A biased BB OPA627AU op amps.
They are both outstanding sounding amps, and choosing one over the other is very difficult indeed!
The Asgard has a warmer and smoother overall sound, very slightly less treble extension, and slightly less dynamic punch than the modded M-stage. It has a softer overall midrange, but at the same time the mids seem to be just slightly more detailed, and slightly fuller than on the M-stage. The Asgard also sounds much better after it has heated up completely. When its cold it sounds sort of flat and dull, IMHO.
The modded M-stage sounds slightly more lively, slightly punchier, and has slightly more bass punch than the Asgard.
The M-stage also has a very slight edginess to certain vocals that the Asgard does not exhibit. The M-stage can be very slightly more fatiguing than the Asgard on some material.
The soundstage is extremely close on both units. The Asgard may have just a touch more soundstage width than the M-stage, but its close. The M-stage has slightly more "air" in the soundstage than the Asgard, but again, its very close.
The Asgard runs much hotter than the M-stage, even though my M-stage is biased into class A with two 3.3K resistors.
The M-stage sounds slightly better with the K702's, and the Asgard sounds alittle better with the HD600's, but both headphones sound great with both of the amps, to be honest.
The M-stage drives my Beyerdynamic DT880/600 ohm version alittle louder and with slightly more authority than the Asgard, and about the same or maybe alittle less than the Headroom.
The DT880/600 probably sounds alittle better through the M-stage than through the Asgard, to be honest.
Both of the amps slightly surpass the sonics of my Headroom Micro Amp.
The Headroom does have the most output power, believe it or not!
The Headroom is a very powerful, punchy little amp that sounds great with all of my headphones, but it can sound slightly more edgy, more forward in the upper mids, amd slightly more closed in than either the Asgard or the M-stage. Believe it or not, my Beyerdynamic DT880/2003, and Beyerdynamic DT880/600 ohms actually have a slightly better synergy with the Headroom than either of the other two amps, for some strange reason!
The M-stage and the Asgard have a slightly smoother and more natural midrange, a wider soundstage with a little more "air" than the Headroom. The bass on the Headroom is close to the Asgard, and the M-stage may have slightly more bass punch than either one of them.
To be completely honest, I do not really have a preference for either amp right now.
This has been a very interesting comparison to say the least!