Any one using 2 separate amps using a/b switch to same speakers?

I was in a similar position a few years ago -- wanted a switcher to change between a tube and a solid state amp.  One of my preferred dealers, who's opinion I give weight to, said that there was no way to do it without degrading the sonics.  I never took steps to confirm that and just stuck to switching out speaker cables when I switch between amps.  However, both amps are hooked up to the same preamp, so no cable switching there.

Good points. My pre does have two amp outputs, however, the second goes to my sub.  Switching out rca’s And Bananna plugs are really not that big of deal. 

You might try a TC-7220 2-Way Amplifier Speaker Selector Switch Switcher Comparator 

I am pretty far down the Audiophile food chain but,I use it to select between a Primaluna Prologue 5 and Emotiva XPA-100[x2] amps.

Niles Audio SAS-1
To be caution most tube amp and some SS amp will damage without load.