7 channel vs. 5 channel plus 2 channel combination

I'm trying to set up a 5.1 system in zone one, and a 2 channel system in zone two. I have a pre/pro with separate zone capabilities. (Onkyo PR-SC 885). I'd like to power both zones on a 7 channel power amp if possible. I'm concerned however that when switching from zone 1 to zone 2 or vise versa, the power amp will already be powered up from the previous zone. Feeding a line level "turn on" transient signal from the preamp into a powered up power amp may cause popping and possible speaker damage etc. Can I use a 7 channel amp for two separate zones or should I stick with separate 5 channel and 2 channel power amps.

Thanks for your response.

Usually, zone 2 is on all of the time. It's a serious waste to have all 7 channels on all of the time.
Another problem is too many times you turn off the theater and turn off zone 2 also.
Either way will work but again its an issue of leaving it on,,,which is very little power in idle but it will need to be on and ready for dual use. It wont cause any damage to speakers though. The 5/2 idea is good again for not powering un-used channels but after that its about the only real benefit, those on a save the planet green crusade may disagree and if you do go the 7 channel route, just hug a tree and Al Gore will forgive you :)