Another pre-amp integration question

Hello everyone, sorry if this a dumb question or if it has been answered a million times (or both). I just ordered an Audio Research LS-12 and plan to put it in my ht system. My question is what will I set my processers' volume at? Being that these "low level" outputs are variable via the volume control, I dont want to damage anything by cranking up the volume too high on the processer. Again thanks for listening and I apologize if this is an ignorant question.
When listening to HT, you should set the LS-12 volume at some easily repeatable setting, 9:00 possibly, and then go through the processor level adjustments. Everytime you use the system for HT, select the appropriate input on the LS (connected to the processor's front channel outputs) and then return its volume control to the position that it was in when you went through the processor channel level adjustment. Good luck.
Is it me or will Jcbtubes' solution not work. Please forgive all inaccurate units of measure in the below example, it's just to explain with.

Say the 9 oclock position of the preamp amplifies whatever comes into it by 2. Say you level it at that position, and say the volume of the HT receiver/processor is at a volume setting that puts 2 volts to your preamp. So this would be 4 Volts out of your preamp, and whatever speaker volume this generates is matched to the other speakers (being powered presumably by the receiver).

But now you turn up the volume level of your receiver, which now gives 2.5 volts to the pre, resulting in 5V output. There is no guaranteeing that the output of your 2 main speakers when given 5 volts will still match the other speakers' output when given their dose of this new volume setting from the receiver. You would have to level the sound across several volume settings to make sure it happened to work out, and I doubt it would. I think this is the same type of math that makes a 40 year old exactly twice as old as a 20 year old, but only for that year. You don't know what those extra years will do to the geometric ratio.

I would recommend finding out what unity gain is on the pre, and always setting it (and leveling it) to that when you use your receiver. This way your voltages are always being multiplied by 1, and therefore will always linearly match. Either that or just use the HT Passthru input on the back of your pre ;-)

I'm not 100% confident in this theory, someone please call BS if it is.
Thanks guys for your input. I probably didn't word my question right. I will use the theater passthrough when listening to HT. I was just wondering when listening to 2-channel music, what to set my reciever volume on and is it possible to send too much voltage to the preamp by turning the the recievers volume up to high. Thanks again for listening.