Yes, you are right rharv, unchecking the 'record IM' box is a workaround and recording the dry signal is probably best in most situations. In this case, though, I use some effects in Guitar Rig VST plugin that I modify dynamically during recording using an expression pedal (Wah-wah and pitch bender). Hence I really need to record the wet signal.

I however discovered that the fact that the M-Audio FTU card has several output channels solves the problem. The "Input Monitor" realtime effect sent from RealBand/PT always goes to the same output pair as the input (i.e. output 1+2 for input 1+2). If I however assign all audio tracks to a different output channel, (e.g. output 3+4), the problem disappears.

Thank you all for your help!

Regards
Bjorn