Agreed with the post above, the USB format still offers SOTA sounds. I have owned all 3 of them and from my listening, I found this in order of preference for the Pink Faun bridges:
1. Ultra USB bridge (built in OCXO and UC power)
2. USB v2 bridge (with the new firmware)
3. USB v1 bridge with OCXO card plug-in
I've also listened to the PF i2S bridge too but not in the same system. I think it slots in around the 2 level. i2S is good but is apparently very sensitive to connection disturbances.
To get the most out of USB, one has to experiment with external power and cabling, both of which makes a difference.