Once I upgraded my network players (to Sonore Ultrarendu) I found the Gen 5 USB input to sound the best on Yggdrasil. I still use AES for mty CD transport but am using it less and less these days. YMMV.
I have Yggy A2 with USB Gen 5 upgrade.
I was also thinking of upgrading my network player from a Logitech Transporter , possibly to an Auralic Aries G1/G2, so I was interested in Ableza's findings on USB.
(I have also read good things about the Sonore Ultrarendu).
I have no experience of using USB input with Yggy, but having tried AES, RCA and BNC, my clear preference is BNC.
I am fairly sceptical about fancy cables, but I bought a DH Labs Silver Sonic D-750 BNC to BNC cable. I got a deal on eBay
I know many prefer AES, but on my system, it sounds slightly 'thin' compared with BNC, with a bit more high frequency bias. I occasionally switch from BNC to AES if a recording is a bit 'muddy'...
Apologies for lapsing into audiophool terminology, but I hope it makes sense.
I had the USB upgrade done at the same time as the Analogue 2, as it made sense to do both while Mark Dolbear at Electromod ( UK Schiit distributor) had the unit open.
It seems that Mike is reaching the point where USB may even become the preferred connection!
I will get a Schiit CD transport as soon as it becomes available, and Mike has said this will definitely have a USB output.
I have a lot of faith in him getting it right.