Hello Aaron: allow me to expand on the gamma 2.
I ended up purchasing John's DAC. It arrived today and I was not disappointed. Warning: I have limited experience with DACs but I have listened enough to understand the wow factor does not apply. Better? absolutely. Worth it? yes, IMHO.
I did compare it with the Compass using the Earth HDAM on neutral settings and my Stax Sigma Pro's.
I compared it with my favorite music, including Vivaldi's Stabat Mater, his cello concertos performed by Yo-Yo MA, and several of Bach's Cantatas. Also listened to Beethoven's Kreutzer violin sonata with Gidon Kremer and Martha Argerich.
I did not adjust for equal volume and that adds another dent to my credibility.
To me, there is no question the gamma 2 is superior. The 3 different filters sound similar. The differences however are there, but subtle. I don't know much about electronics; I am an amateur musician, not an audiophile, and to my ears this is how they sound:
Filter A has a bigger soundstage and sounds almost tubey. very pleasant.
Filter C has less of a soundstage, sounds more forward, has brighter treble and is a little more detailed.
Filter B sounds somewhere in between.
The Compass sounded a little sharper and not as musical in comparison, using neutral settings, but I do want to emphasize the difference is not huge.
Piano and strings sounded beautiful with the Gamma 2; choir and individual voices did too. Soundstage was large with the Sigma Pros, and sounded even larger when connected to the Gamma 2. The details between different instruments were easily distinguished. The Stax Sigma Pros are known for their soundstage and non fatiguing sound, which makes listening to acoustic and classical a real pleasure, although they roll of at the extremes. The gamma 2 DAC combines well with them.
Although they don't have a built in amp, the G2's can power low impedance headphones. It even powered my DT880 250's although not at very high volumes, but louder than I usually listen. The level of detail with this phones was indeed impressive, far more than the Sigma Pro's but not as sweet and enjoyable. The Sigmas have this beautiful non fatiguing and addictive sound that grows in you. If used this way (I am sure IEM's would be very easy to drive but have not tried my ES3X), you have to control the volume from your computer since the G2 does not have a volume pot.
I would be happy with the Compass, but I am much happier with the Gamma 2. Is it a whole lot better? Again,the difference is enough to be noticeable and to allow me to enjoy my music even more. I think I will keep it for a long time.
As far as quality, it feels solid and well built. MisterX and AMB did an excellent job and IMHO, they sure have a winner.
This DAC should be considered by anybody on a budget looking for great quality and sound for much less than commercial brands.
Another late entry;
man, my speakers sound better too! I am surprised on how much more detail and soundstage the G2 has when compared with the Compass. Since my living room is large and has quite high ceilings, it sounds better when I use Filter C settings. I have been skeptical of DAC's price/performace ratio; less skeptical now.
When I had the Compass connected I was always fiddling with the treble because it sounded too bright and a little harsh. My speakers are not fancy (B&W 602's with a Velodyne subwoofer) because I usually can't listen at high volumes when my wife is around the house.