Brilliant... thanks Mario, that is very informative and helpful.

I see in the channel prefs I can change the bass from -1 to 0... which if I have my Modo Bass vst assigned works fine, but as you say a regular midi synth would then be 'wrong'.

So it looks like using a GM is probably best in BIAB and then finish off in Reaper using my dedicated vst's.

I've experimented with readdrums... but I'm trying to get a consistent (and editable) drums and bass tone for each song, much as you would get with a live band if that makes sense.