You're right as long as USB device is powered externally and not via computer motherboard, eg. your wifi USB suggestion. Your point on grounding is very important - I use a filter that legally cleans ground and prevents grunge from going back.
I speak under correction: best interface is no audio output device at all. That is, use a DAC capable of USB or Ethernet input. I haven't tried this but would be great if others can share experiences.
USB DACs (unfortunately limited to 16/48):
1. Bel Canto DAC 3 ('reclocks' data to minimize jitter)
2. Apogee mini-DAC
3. Wavelength Audio (multiple)
4. Audionote DAC kit 2.1
Ethernet DACs:
1. Slim Devices Transporter and SB3 (Transporter is an interesting choice for minimal jitter - you get digital outs that can be slaved to another DAC's clock, eg. Emm Labs DCC2 SE).
I hope other manufacturers get this going, esp. USB 2.0 - that way you bypass poor internal samplers and send 24/192 from computer. Challenge is jitter: if DAC doesn't 'reclock' data, you need high quality clock in audio device - I doubt there's anything better than USB Offramp Turbo 2.
I speak under correction: best interface is no audio output device at all. That is, use a DAC capable of USB or Ethernet input. I haven't tried this but would be great if others can share experiences.
USB DACs (unfortunately limited to 16/48):
1. Bel Canto DAC 3 ('reclocks' data to minimize jitter)
2. Apogee mini-DAC
3. Wavelength Audio (multiple)
4. Audionote DAC kit 2.1
Ethernet DACs:
1. Slim Devices Transporter and SB3 (Transporter is an interesting choice for minimal jitter - you get digital outs that can be slaved to another DAC's clock, eg. Emm Labs DCC2 SE).
I hope other manufacturers get this going, esp. USB 2.0 - that way you bypass poor internal samplers and send 24/192 from computer. Challenge is jitter: if DAC doesn't 'reclock' data, you need high quality clock in audio device - I doubt there's anything better than USB Offramp Turbo 2.