I use a Bryston 2 way speaker switch with a Bryston 14B SST, Von Schweikert VR4 III SE and Cambridge Soundworks Tower II loudspeakers in another room. These switches are well made with heavy duty gold plated contacts. I haven't noticed any degradation of sound quality with this unit, but FWIW I haven't heard any differences between high quality speaker cables or interconnects either.
http://www.bryston.ca/swisel.html
http://www.bryston.ca/swisel.html