Hi quality A/B switch?

Newbie here. I have 2 systems but only one set of speakers.
I would like to know if there is a high quality A/B switch that will allow me to switch between the 2 systems without a great loss of sound quality. I've tried the Radio Shack unit and found it to be lacking. Any help is greatly appreciated.
A long time ago I was looking to do the same thing, other than commercial audio switch boxes I couldnt find any.So, what I came up with was a 2 brass Double Pole knife switches, one for the left channel and one for the right, brass is a good conductor. I treated them with contact enhancer. Now there are a few things you must be carefull of, always have your amps shut down before you switch. If you have a tube amp never have it on without a load or connection to the speakers, also I made a protective plastic cover for the Knife switches so nothing would fall on them and short them out. Here is a link and part # for the switches .hhttp://scientificsonline.com/Product.asp?pn=3038806&sid=yahoo&cm_mmc=yahoo-_-cpc-_-edmu-_-knifeswitches&OVRAW=knife%20switch%20with%20gold%20contact&OVKEY=knife%20switch&OVMTC=advanced&bhcd2=1133107579
Item# 3038808 Knife Switch, Double Pole

Thank you for your reply. This looks to be a good solution. I appreciate your answer. I'm a vintage audio guy (well, it's not vintage to me) so I am very concerned about keeping things in order. One system is all Phase Linear which I took out a personal loan to pay for back in the day. The other is comprised of early 1970's McIntosh components, the ones I wanted when I was in my early 20's but couldn't afford even with a loan. I just can't see hooking either system up to inferior speakers & I only have one good set, hence the question. I just can't justify 10's of thousands on today's speakers.