A rookie question re two amps, one pair of speakers

There might be a better solution. What amp are you using for your 2 channel listening? Does your HT Receiver have line-level pre-outs for the front speakers? 

You might be able to re-cable it using the 2-channel amp to power the front L&R speakers for both 2-channel listening and when listening to multi-channel HT from  the receiver.

Thanks for the response.

Actually, up until recently, I had been doing just that.  It worked all right - my only issue would be that my front mains would be getting twice the wattage of the other channels in HT mode.  I've been having some issues with my NAD receiver lately though.  For some reason I get a humming from the preouts of the receiver when I connect it to my outboard Rotel amp. I've done some problem solving and I'm 99% sure it is the NAD preouts.  So at this point, I just want to completely remove the receiver from the 2 channel system (or as much as possible).   I have a separate DAC/Preamp that I can connect directly to the Rotel amp.  I just want to know if I can share just the front main channels with the NAD receiver and the Rotel amp.

Thanks again.

One amp would be for my 2 channel system and the other (a receiver) would be for my home theater system. So long as I’m not powering both amps at the same time, is it safe/ok/advisable to connect both amps to one pair of speakers?

In one word NO!!
As one of the amps will be trying to drive the others output stage, even if not on.
Unless both amps have a speaker terminal disconnect relay when not on for both + and - terminals, only a tech will be able to tell you.

Cheers George

George is right, do not connect two amp output to one pair of speakers! this topic had been discussed many times, best way to do it is using a speaker selector switch.
I had use a Niles SPK-1 years ago, it switch the connection automatically from the receiver 12V trigger.
https://www.google.com/search?q=niles+spk-1&ie=utf-8&oe=utf-8