I agree 100% with you that this should be tested more thoroughly. This was just a 5 minute test that I put together. Unfortunately I don't have a DI box so I could try what you described.
You do not need any. Use the Direct out from the Profiler
In any case I'm happy with the upgrade and that's what's matters in the end, doesn't it?
Not really, since you started a thread to advise about a cable which makes a difference, so you've make it bigger than just your satisfaction
Also, if I was happy for something I'd really wanted to know whether I'm making things up or not, specially if it took me only 5'. YMMV, of course