IIRC, it grabs the signals before the sound card messes with them.
Ran the turntable into the phono jacks on an old Sony Str AV-760 then hooked the tape out, where the signal comes out to a tape deck, to the PC's audio in jacks. Worked great.
CAUTION ~ Don't set this up in the middle of your damn desk so you can't do anything else until it's broken down.
