Switching Pre-Amp Inputs using NDS

I've got my NDS set up to control my 552 pre-amp via n-stream, which works fine for volume control. However, it doesn't seem to work how I would think it should to control inputs.

I have the NDS set up to play into the CD input on the 552 and my turntable set up on the Tuner input. I can start playing streamed music via the NDS then switch to the turntable no problem, but then cannot switch back again - changing off the input the NDS is playing into seems to kill the streaming music, and pressing UPnP on n-stream takes you back to the start of the music selection process, making A-B-A comparisons difficult.

This works fine via the 552 remote, but as everything is in a separate room to the speakers, not so easy to use.

Obviously not a massive issue, but anyone got any ideas?

I have the same issues when trying to compare the NDS analogue output to it's digital output into a Hugo.