I guess I'm confused by all of this, the sub will not wake up until it receives a LFE signal from either a CD or Movie. Depending on where you have the crossover, it is possible you won't get anything in those lower frequencies. Many CD's never get that low anyway. If you cranking up the volume to try to wake up the sub, that is the wrong approach. +5 seems high, I would try starting around 0dB's and then adjust the sub volume until you've achieved an SPL of 75dB's or so, if you have a RS meter to check. When I owned a 350, it was about at the 12 o'clock position, and the AVR was on -2dB's to achieve 75dB's SPL. Make sure you have your crossover out of the way and turned clockwise to the max.
Put a movie in with lots of LFE and the 350 will wake up.
