Just make sure the outputs you are going to use to send the bass signal out of the Profire are configured properly in the Profire Control Panel (ie. make sure that pair has a dedicated pair of software returns, not mirroring something else). In my case I just make sure hardware out 7/8 are set to software return 7/8.
Then in Reaper, take the bass DI track, click the I/O button, add 7 or 8 as a new mono hardware output for that track (depending on which one you want to use, I use 7) and disable the master/parent send.
Then create a new track, set it to record the input from whatever channel you are plugging the Sansamp into. Say for arguments sake you plugged the Sansamp's output into Input 1:
Now wire everything up and hit record:
I got one question, sorry I haven't used a reamp box, but how is the line output (1/4" jack) going into the XLR of the little labs?
TRS to XLR cable. Same as you might have going to your monitors.
How about if I want to reamp a 5150 and just use the preamp section and use impulses for the cab?
if you want to use the preamp, the front; if you don't, to the fx return.
Perhaps this guys' fx loop is not working properly. I have it sent from my profire to the guitars Higain input and out the fx send into my profire and not getting a signal. =(
Amp must be turned on completely (ie not on standby) and the volume has to be turned up. This is why you need a cab connected. The 5150 might even have a preamp out on the back I can't remember, worth trying that as well. But don't take it off standby without having a cab connected or you will fry the dudes amp.