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

One of the problems with a switch is that it can introduce an unwanted/additional sound artifact. Unless you are a dealer that needs to switch between different amps/speakers, it would be better if you just re-cable each amp separately.
Probably not what you wanted to hear, but I had to say it.
B
PS- I own both SS and Tube. I use the tube amp in winter and SS during summer months. It's nice to change things around.😉

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.