[N.B.: Fanboi index knob stuck at maximum]
I've been listening to the new AVA digital preamp for a couple of weeks. Since I'm also using the headphones, I have kept the Vision analog preamp on the signal path and I have been using the new DAC/Pre as a DAC, replacing an UltraDAC with its lovely little tubes inside. I suppose this is not a divorce, more like polygamy. My main motivation was convenience in the digital inputs, steering away from tubes for non-audio reasons, and an eventual arrival of balanced (ie XLR) amps someday.
The new DAC/Pre/etc is very, very, very quiet. I turn the knob on the analog preamp, I feed 0's to the digital pre and set its volume to maximum at 63 (= 2
6 - 1), I turn on the 600R with its 50ish db of gain, I put the analog knob to full blast for its 20db of gain, and I can't get either my gold-plated ears or the radioshack spl meter to notice that anything is turned on.
Sound? The new dude sounds wonderful, I'm "sure" it sounds better than the UltraDAC but to me they're close, not so easy to A/B DACs anyway, my room is not good enough for ultimate critical listening, I'm not a teenager anymore, and some other excuse I'll think up later. Did not use the comparator to compare with the UltraDAC because that would have been rude. I'm sure the tubes--and the vintage--of the old dac has to have a higher noise floor, but it was never really a problem. So to me the absence of noise I can measure is just one more thumbs-up to the engineering achievement that this device represents.

I think Area 51 sent a noise vacuum pump blueprint over to Minnesota, but Frank always has some cover story, nowadays probably something about Dan being a great engineer, proper testing, vetting before shipping, strategic bypass caps etc. At least the thing doesn't hover when I plug it in...
Is it worth getting? Superquiet, it plays all the ultrahighrez stuff that Shannon's theorem gives as superfluous (but not for editing! there the high rez officially matters), it gets out of the way, sounds musical, etc. If you don't use headphones, then it it also a (digital) preamp so the cost is offset by the complete management of delivering a digital signal to an amp without any additional cha$$is. It's not cheap by some standards (eg my paycheck) but man oh man, buy once and be done is what I see here. Thanks to its galvanic isolation and probable future-proofing, I see no reason to ever sell it.
Other non-golden-ear details...to quote Dave Jones, "don't plug it in, take it apaaht" was done, and this thing inside looks like ice cream. Like the AVA Comparator it has large clear labels by each component, generously spaced apart, soldered with joints to die for on PCBs thick as pancakes, capacitors you can't take home to Mother...ah. Servicing this beauty would be a breeze, but it'll probably run well into Captain Kirk's century from the looks of it. I had to talk myself into putting the cover back on and just listen to the thing.
OH AND IT HAS A TOUCH SCREEN
I almost forgot. It has a touch screen.
I suppose someday I'll plug in some balanced amp and give the XLR outputs a shot, skipping the analog pre. I don't know if my ears will be able to tell them apart, but the electrons probably will.
It's been a bit of a wait--dac chip factory on fire, covid, trade blocking, you name it--but to me the wait was worth it. Thanks Frank!