Do I need to use a speaker selector?


I have two audio systems. My question is directed to my secondary system, which consists of a pair of B&W 805 speakers (8 ohm, nominal) and a "whole-house" speaker system comprised of 7 pairs of speakers, each connected to a Niles Impedence Magnifying Volume control. The whole-house speaker system is supposed to present an 8 ohm load to the amplifier. I am purchasing a PS Audio GCA 250 to drive the B&Ws and the whole-house system. Here's the question: do I need to use a speaker selector box, or can I hook the B&Ws and the whole-house speaker wires directly to the amp? If I connect direct to the amp, the load it will see may go as low as 4 ohm, nominal. PS Audio claims that the GCA 250 can handle a load with impedence less than 1.5. Am I missing something, or can I skip the speaker selector box and wire directly to the amp? Any thoughts or suggestions would be greatly appreciated.
tin_ears
Thanks, Bob. I had not thought about the damping factor. But you are right, the whole-house system is more about background music and casual listening. I have a separate system set up for active listening where performance is the goal. A follow up question -- the speaker selector box I have is the Rotel RSS-900. It has impedence protection circuitry built into it. Which do you think does the most sonic harm: using the Rotel Speaker Selector with additional "stuff" in the signal path, or compromising the amp's damping ability by hooking up the speakers in parallel?
Why not buy a cheaper seprate amplifier for the distributed audio. Connecting a string of speakers and the B&W's to a PS with or without the speaker selector box is like using a BMW to do farm work.

For distributed audio you could use the new Parasound 275 amplifier which has a 20 and 40 Hz filter, A&B speaker outputs, and a low impedance switch. This amplifier is really designed to do what you want it to. A cheaper solution would be one of the AudioSource amps. I use them in lots of installations for background music because they are relatively inexspensive and have features that are useful in multi zone aplications.

My 2 cents.
Hmm, don't think I have ever heard the B&W speakers compared to a farm implement. I use the B&Ws in my study and find that they do pretty well when match up to good electronics. I do agree, however, that the PS Audio amp is overkill for the distributed whole-house system. But since I use this amp to drive both the whole-house system and the B&Ws, I want to use a decent amp.
Not knocking your B&W's. The introduction of either a selector box or direct connection of the distributed audio to the PS will have a deleterious effect on teh sound comeing from the B&W's.
Yeah, I suppose I know you are correct. I am just in denial because I want to find a "convenient" solution. Besides, I don't have room for a third amp....or, maybe I do....