speaker switch box quality

I am looking at adding a speaker switch box so that I can hear my stereo outside. Will this effect the sound of my stereo inside?
If you are very serious, most likely yes. I use an Adcom GFS-3 to do exactly that. It switches from my living room, to my deck speakers. Its not my main system. I can't say I have ever noticed anything negative with it, but, I don't use it for critical listening. I would think it would do a nice job for most people.