External processor loop of VTL 5.5

To those who own VTL 5.5 preamp, just this question. If you connect your home theater processor to the VTL's external processor loop, does the 5.5 need to be switched on while playing the HT? Your experience will be of great help.
I have a VTL 2.5 and use a surround processor/preamp connected to the processor loop on the VTL (HT bypass). The VTL needs to be on to pass the front channel signal to my speakers. I think the 5.5 operates identically except, of course, it sounds a little better than the 2.5. This isn't a bad thing, IMHO, since the signal goes from your processor and then through the VTL's tubed stages before going to your amp. The sound is better than straight from my processor to the amp on my system. Hope this helps.