Signalink, Rigblaster, all that... the XGGCOMS and Donner interfaces just work, good KISS setups. I've used both.
Most hams I've had PSK31 contacts with, those from countries other than the USA, generally use homebrew interfaces that are similar to the Donner interface, or some variant. I note they seldom use the more complex interfaces. One ham I had a contact with, a guy in Cuba, used a little 2" speaker glued to one end of a short piece of 2" pvc pipe. On the other end was a little cheap computer mic stuck in the end with some foam rubber. This gave an interface with total electrical isolation as well as isolation from room noise. He had two of these, one going each way between computer and radio. You just can't get any simpler than that. And it worked just fine!
Sometimes we make things too difficult for ourselves.