I just discovered that I can't run the DI from my head (Eden wt550) directly into my Presonus Firepod--horrrible high whine (happens with all my heads and the Firepod). Apparently the solution is either a passive DI with two outputs and one in, or a splitter? Any Presonus Firepod users out there using a DI or splitter for recoding their bass? What are you using?