A coaxial switch would be the best solution but if you make sure you turn off the amp you aren't using, it would probably be OK.
RCA Y- cable or is an A/B switch required?
I would like to connect my CD player to two different preamplifiers (one stereo connection for my surround sound receiver and one stereo connection for my vintage McIntosh gear). In the old days, we simply used an RCA Y-cable for each channel, but I am curious if the sound quality or a possible line level instability might arise.