Heh...I suspect you'll get some different opinions on this one.
I run a V3 at 16-bit (waiting for the MT2496 to sort itself out before I move to 24-bit). I find the V3
not at all similar to the AD1K sonically. The V3 is very detailed and natural sounding to my ears, while I find the AD1K less natural, more "hyped" in the lows and highs, but still very pleasing. The 722 has a more colored / looser / robust low end relative to the V3. I'm torn about highs since I've heard two different recordings by both V3/722 - on one I preferred the V3 highs, on the other the 722. Mids seem similar to me - detailed, smooth. Soundstaging - I've yet to find an ADC that presents as coherent a soundstage as the one I hear from the V3. Aside from the V3, I like the 722 ADC better than most others out there.
A bunch of different thoughts on an A/B comparison:
http://taperssection.com/index.php?topic=38265.msg492757#msg492757I don't recall which source was A, and which B. PM or email Scott Brown and he might still remember. Better yet - maybe he or someone else will re-post the comp for you (I don't have it anymore).
I don't know of any AD1K v. V3/722 comps, but I know there are a couple 722 v. V3 comparisons out there. Maybe try a search for 722, V3, and comp and see what comes back.