I have both the Master 7 and the Reference 7 in house at the moment. A few days back, when I first plugged the Master 7 in (using Audiophileo + Aqvox > Balancing Act > HD800) I was taken in for a bit of a whammy. I first noticed the considerably (only by audio-patter standards) widened soundstage (from the PWD MKII + bridge). I chalked this up to Amber Rubarth's wonderfully recorded binaural album (Sessions From the 17th Ward) and to speak the truth there hasn't been a DAC, amp or headphone that sounded poorly with this album. It's since become clear, however, that both the RE7 and Master 7 have an elongated left to right pan compared to my other DAC's, in addition to a superbly open, 3D soundstage.
The second aspect, and this came more as a surprise, was the great body the Master 7 showed. The PWD was the de facto champ in the body/solidity department and at first glance this was matched or exceeded by the M7. Lastly, the M7 is very resolving. It digs deeper than the RE7 and consequently is less forgiving. I'll need to return to the M7, after spending a few days with the RE7 to confirm this point and hopefully gauge the degree of this improvement. I believe it has mostly to do with leading edges; a sharper introduction of a new sound, particularly during variegated passages or on finely nuanced albums. I can say, however, without question I prefer the more rounded, bloated even, bass presentation of the RE7. For me at least, this is a welcome relief from the Delta Sigma signature I've inadvertently grown accustomed to.
Where both of these DAC's are really tingling is in their tonality. This really is an area that is difficult to put your finger on, and undoubtedly is prone to inexorable points of view, but both of these DAC's coerce you to put down the book, turn off the monitor, nestle into your favorite cranny and listen...closely. It startling sometimes, and in this area I cannot say that the one (M7) is any better than the other (RE7). If the RE7 exhibited just a bit more definition in the unveiling of a new sound, just a hair more clang and emergence, I'd forget the M7 and the way it dredges details out of the muck of a recording. As it stands I need more time or an i2s input (RE7) so I can finally give Steve over at offramp the green-go.
Edited by ericfarrell85 - 10/2/13 at 7:35pm