Onboard SPDIF such as HifiBerry vs USB-SPDIF converter

[itsikhefez]

Hi

Are there any advantages to using an onboard SPDIF such as the HifiBerry Digi+ vs USB-SPDIF converter such as the HiFace or V-LINK?

My current setup is-
RPI+RuneAudio
Musical Fidelity V-DAC + V-PSU (connected by USB)
Denon PMA-510AE
Quad 11L speakers.

The USB implementation of the V-DAC is rather poor, and I expect it to benefit from being connected via SPDIF.
The question is, which is the better approach considering only sound quality-
An onboard SPDIF or a USB-SPDIF converter?

Thanks,
Itsik

[Aquarius]

i2s signal is supposed to be better than USB. Plus, Raspi B (i.e. not "+") had issues with high res files on USB, so it seems. (lot of people had pops and clicks when using USB).
since the Digi is so easy to use even easier for the B+), I don't see any drawback to using it.