Sharing amp inputs between two pre-amps

Tried searching for this in the forum but came up empty.  Limited space is forcing me to share my system between my TV and audio system.   The amp is solid-state with a single pair of inputs.   I currently have a solid-state pre-amp hooked up for both needs but I have a tubed pre-amp that I would like to use for the audio portion (CD / vinyl) only.  Would it be possible to use Y-adapters on the amp inputs to share them between both pre-amps?  Only one pre-amp would be on at any time. 
It’s not usually a good idea to connect the outputs of two components together, even if both of them are never on at the same time. And of course a Y-adapter would connect the outputs of both preamps together, in addition to connecting them to the amp. Depending on the specific designs the consequences of doing that could range from degraded sonics to damage.

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,

Thanks, Al, for your thoughtful and detailed response.  I will probably abandoned the idea rather than take a chance on damage to my gear but I will definitely have a look-see at those switch boxes you referenced.  Cheers.

There is a company named Zektor that makes very high audiophile grade switching panels among other things.  I have one called a MAS7.1, so named because it can handle up to 7.1 channel analog surround system.  It will also switch three unbalanced stereo inputs into one output (or vice-versa) using silver make-before-break contacts so there is absolutely no switching noise.  Each contact is a straight through connection.  The switch will also handle switching for 5.1 or 7.1  analog outputs in a multichannel system.  It's price is I believe around $800 but they are sometimes available used for much less.

Only something of this quality design and construction should be used to do the switching you wish to do.