Audio-GD M7 vs.  SA-2
Had a DAC-off here on my rig (4-45 / HD800 on Abyss). The M7 was fed from the OR5 with HDMI i2s (I'll explain later). The SA-2 (musical series) was fed with the BNC from the OR5. The M7 could have had an advantage here because of the i2s; but it shouldn't have been that much, or maybe there really is that much of a difference?

The M7 was warmer sounding despite it being a "reference series" DAC. However, the M7 did have slightly better or sharper delineated attacks. So maybe the "musical" series equipment is just a tad softer. The M7 had a wider and much deeper presentation. M7 also extracted more plankton - was able to hear ambient cues, noise grain, etc. better.

The differences were shockingly notable at the turn of the input dial on the 4-45. Whoever thinks all DACs sound the same or are indistinguishable should have tried this (or used more resolving / better downstream gear.)

AK120 vs. AK240
The AK240 has all sorts of new functionality, mainly the ability to stream wirelessly (cool), and native DSD playback (don't give a sh1t). Streaming DSD will suck up battery power faster. Still the unit is expected to last for many many hours. However, it my understanding the DSD bit patterns transmitted through the air may fry testicles or cause insanity.

The AK240 is slightly more powerful than the AK120 (spec-wise), but honestly, I think it's a tiny step back in sound quality. The Cirrus DAC chips I've heard have never sounded nasty, but they have a tendency of sounding a bit on the boring side. This seems to be the case here. They should have stuck to Wolfson of the AK120, but maybe the Cirrus stuff gave them the DSD functionality that they needed?

BTW, I love the futuristic design and charging dock.

HDVD800
I was rather surprised because this sleek rectangular box exceeded my expectations. I tend to shun products which receive a lot of hype from the usual sources, but this DAC/headamp combo unit seemed to be a really good match with the Sennheiser headphones (HD700 excepted, mainly because the HD700 sounds bad despite whatever is feeding it.)

The SE output wasn't all that great, kind of murky sounding. The balanced out was pretty darn good. Really nice clarity, separation, blackground, and best of all fairly smooth sounding. Uncanny refined for solid-state. I didn't get a chance to try this amp with my set of "marginal" recordings, but given that the HD800s I tried used were in 100% stock form, I'm tending to believe it would be a good match. I mean, the HD800s were still bright, but at least they weren't difficult with glare, hardness, etc. Probably still a tiny of grain.

No, this is not the last word in maximizing the HD800's potential, but I felt it was pretty darn good in synergizing with the HD800. But then again, it would have been pretty darn embarrassing for Sennheiser to make a DAC/amp that sounded like sh1t with their headphones. I recognized some of the same reps, and I'm sure Sennheiser has seen it's share of embarrassing moments, i.e. when people told them their HD800 sounded like sh1t out of their amps or when people pointed out to them their Anax mods.

Chord Hugo
No. Just no. And no. Volume control is stupid. Inset phono sockets are retarded. If Steve Jobs saw this design, he would have strangled the designer like how Vader strangled his admirals. Seriously, we are talking about Fisher-Price school of design here. Sound is at least is not horrible; but lots of better sounding choices (Geek, Dragonfly, Dacport LX, etc) for much less money.

Questyle Amp and DAC
I don't know which was to blame, but this combo sucked ass. Definitely one of the worse things I've hear at the meet. If some solid-state equipment sounds etched and nasty, this takes it in the other direction. The bass wasn't gooey or anything, but, smooth, dark, dull, overly overly polite and forgiving. Almost as bad the RSA Darkstar (yes, the Darkstar really is that horrible.) I used Paradox Slants and Enigma (and known tracks) for this evaluation.

Chord Hugo
No. Just no. And no. Volume control is stupid. Inset phono sockets are retarded. If Steve Jobs saw this design, he would have strangled the designer like how Vader strangled his admirals. Seriously, we are talking about Fisher-Price school of design here. Sound is at least is not horrible; but lots of better sounding choices (Geek, Dragonfly, Dacport LX, etc) for much less money.

+1

Phonitor 2
A solid amp which sounded good with the stock HD800s (I was unable to use my suite of test tracks). Based on long ago memories, seems to better than the 1 - smoother presentation. Nothing special amp-wise, but very competent by itself. Actually very good depth even without the knobs activated. The reason to get the Phonitor are the dials. Probably the best headphone crossfeed in the business I've heard. If you are into that kind of stuff. The adjustments are subtle; and that's a good thing.

EAR
EAR combination of DAC, headphone amp, etc. All in chrome. We affectionately called it the "cylon" equipment. This stuff just sounded weird. Seemed to have a strong emphasis on the middle-midrange and a de-emphasis on the bass and treble. Other aspects sounded good though. A slight tubey touch with inner warmth and wetness reminiscent of the DNA Stratus, however without the clarity, separation, microdynamics, microdetail, etc.

I couldn't figure this out, especially the odd tonal balance thing... until I realized how well the EAR stuff matched with Grado headphones. Makes perfect sense now. Unfortunately, the Grado thing was almost 10 years ago.