This has probably been discussed before, but I couldn't find it.    My question is, if I have an external DAC ... does the computer sound card not matter AT ALL?   I can just buy the cheapest, worst, card?...or does it have SOME effect?

Considering that I have EF-5 Amp already, so (I think) the power needed to run both is present.   So the comparison is mainly sound-wise.     PS: Using ODAC with the EF-5.