Considering you can order any of these unit installed in the card from Auzentech we thought many of you would appreciate the tests.

Tests performed using:
Studio Reference Monitors
Sennheiser HD595
Beats Headphones

AD797A
The AD797 offers tighter bass and a more "glossy" type of sound. Offering a greater level of detail then the stock opamp seems to provide. The AD797 offers great musicality, the toe tap factor. The vocals are pulled back a little more and more balanced with the background. The signature still has that nice layered sound. There was no smearing or confusion present you could turn up the bass, and have even control of the frequency. Some songs were very articulate, you could hear the tubes a frying' in the guitar amplifiers. This make a great little replacement amplifier chip for those on a budget.

AD8620
The AD8620 offered more clarity and increased definition in the sonic response. There were details that easily came through on songs that were unheard or rather unnoticed during other tests. This opamp offered nice balance between Bass, midrange and high range frequencies. This card still exhibits the layered sound-scape when using this opamps but we have more definition and extenstion.
All the tested songs do not seem squashed, everything seems to have its own place in the mix, very open and spacious image presented. These are one of my favorite all around opamps for audio and placed in the Forte 7.1 the combination produced some enjoyable music.

OPA627AU
The 6X7 series are some of my favorite opamps as they have a great musicality to them. We tested out a few blues songs with this opamp installed and what struck me first was the detail and articulation heard in the bass range. The bass drum suddenly had much more character then what was heard before, it was to the point that we listened to the entire song just concentrating on the kick drum.
The 627 produced a nice laidback toe tapping response getting you moving while listening, The imaging was still very layered and deep with this opamp which is very enjoyable.
The 627's brought out more of the rhythm present out front and the vocal a bit back. Cymbals and high hats have great character and articulation. This opamp produced a very warm character when used on this soundcard, offering a nice balance of clarity and details.