What I’d suggest is that you use a line-level switchbox. Assuming all of the connections involved are single-ended (i.e., RCAs) you may want to consider the DB Systems model DBP-2JAU/5 ($110) listed near the top of this page. It is similar to the DBP-2J/5 for which a review and description are linked to, except that it has gold-plated jacks. For contact information go to their home page. I’ve used that switchbox in the past with fine results. The one slight caveat I would mention is that if you attach heavy cables to it their weight might cause the front of the switchbox to rise a bit.
Another possibility, although it costs $359 plus options, is the Decware Zen Switchbox. I have no experience with it, but I’ve seen very favorable comments about it here.
Good luck. Regards,