DAC 3-4k range

I am very partial to the Berkeley Alpha DAC. I've lived with them for some time now and actually cannot think of anything I'd change about it. I continue to develop my system around it and it just keeps getting better. It also has a great volume control so if you care to, you could get rid of the Transporter, get a USB converter to go from a server to the dac and even sell your integrated and get an amp. Simplify and improve quality at the same time. Plenty of reviews, both user and professional, available on the web. Computeraudiophile.com has quite a few users, posted reviews etc.

There are many nice units in the market. Ayre makes a nice one that would mate well with your electronics. Also, ARC DAC8, Bryston - among others, are probably very good alternatives.

Mike

I'm enjoying great audio with the Ayre QB-9 into an AX-7e running balanced with Cardas Clear cabling. But of course that's with USB in asynchronous mode, not compatible with your logitech transporter. It's rumored that the next Ayre DAC may support S/PDIF or AES/EBU input as an additional option.

Barring those, I recently heard a system with Antelope Zodiac Gold running in balanced mode that was also incredible, IMO. Good luck in your auditioning.

It would be a mistake to leave Lampizator out of your considerations. I'm listening to a level 3 with lampizator transport now and it is very good digital.

Audio Horizons Tube DAC 3.1.