2 input sources, 1 output to stereo power amp question

[bjaudio]

If it doesn't jeopardize the sound quality or create problems for the equipment, I would like to toggle the signal between two preamps going into a stereo power amp.
One preamp is for dedicated 2-channel, the other preamp is the front left/right pre-out from my surround receiver.
Currently, I manually switch the audio cables. Is there a quality switch box out there that doesn't add too much impedance, noise, etc. to the signal? I would like to simplify this process if possible. Thanks in advance for your suggestions.

[Face]

You should look into a 2 channel preamp with a home theater bypass.

[Fongolio]

I am using a switch I obtained from Radioshack to toggle two output signals to one set of speakers. Position A sends the signal from my Pioneer Elite AVR to the speakers and position B sends the signal from my turntable/preamp/amp to the same speakers. It's actually a multispeaker switch that I've wired in reverse to make for a multi-source switch. This may work for your application as well. I can sense no signal degradation at all. The switch is a Nexxtech Speaker Selector switch. Here is a link showing the exact switch I've used. It's from Source by Circuit City (they bought out Radio Shack in Canada).
http://www.thesource.ca/estore/product.aspx?product=4000132&language=en-CA&ref=2005