Ok, so I've got some problems using the reaper. First of all, after play anything there's a pretty big delay until i hear it. Secondly, when i play for couple of seconds the volume drops by a certain amount, and goes back up when i stop playing. My signal goes like guitar => vypyr 30 => my computer. Earlier I' ve been using reaper with my pod and it worked just fine, if that matters.
It likely has to do with whatever USB driver you're using for the Vypyr. I'd download ASIO4ALL and try that out and see if it fixes your problem.