When you go from USB to a DAC is it always SPDIF?

No. Other options are:

1) AES/EBU

2) I2S (direct D/A bus)

#2 is lower jitter of course.

Steve N.
Empirical Audio
Manufacturer

I do not know anything about the quality of performance of this item but, as far as I understand, it takes PC or Mac USB out and converts to digital outputs (S/PDIF, AES/EBU, BNC,Toslink).

Maybe someone setting up their own music server will find it useful.

http://www.trendsaudio.com/EN/Product/USB_Audio_desc.htm

What other type of connection are you looking for? Toslink? Balanced? I2S?

Most USB converters go to SPDIF, because it is the standard connection for digital. Also, some like the EMU0404USB card offers a USB to SPDIF, Balanced and optical Toslink conversion.

However there are also USB DACs that accept a USB signal directly. Some of these include an internal USB-SPDIF converter, some better ones use USB-I2S converters which is the native interface of the DA chip (e.g. Wavelength DACs, Empirical Audio, Benchmark DAC1 USB).

As suggested in your other thread, check out out the Empirical audio website and the Computer Asylum. Many questions you might have, already have been answered there. For example these questions surely are answered there in even more detail.

unless you have a USB DAC...yes.