Ok, a sort of useless answer from my side (not expecting the real experience from someone in here) :
All the users of the predecessor of the Phasure NOS1-USB DAC used a (highly) modded Juli@ which was in the DAC, and it was the best.
Compare that (situation) to what you propose would be an apples and oranges thing quickly, because it would imply using another DAC in the first place - although people could use the DAC "box" itself as an interface device because it contained SPDIF-Out. That for 100% sure improved, and legacy DACs became "new" because of it (I had a few reports about it). Still apples and oranges, because this is not how you will be using the Juli@ (you will have it in-PC instead).
Indirectly I should be able to compare all by means of comparing the current USB interface with any of such devices you propose, and then most probably the proposed devices will "lose", but this then depends on the implementation. So, my own USB interface will win the game for sure (everybody will agree instantly that it sounds way bettter than the Juli@ interface), but now it comes down to my USB implemenation against the others (like the HiFace). I am sure my implementation wins hands down in general and I can only imagine how a HiFace (or Weiss etc.) will compete against that Juli@.
Blahblahblah, but the Juli@ should lose because it is in the PC while the others imply asynchronous operation which is better for jitter. However, since async USB implies more jitter once in-DAC we may wonder.
The only more or less comparable situation I encountered myself was using a FireFace800 with SPDIF out against the Juli@, both feeding the same DAC (which was a prototype of the NOS1). The Juli@ won hands down, and was in-PC at that time. But, its output was i2s, and not SPDIF ...
Well, I tried.
Peter
