2 amplifiers connected to 1 set of speakers


I’ve been in the hobby for a few years and my wife asked me a question that stumped me.

Can you have 2 amplifiers, connected via their own individual sets of speaker cables, connected to the same pair of speakers at the same time? I told her I didn’t think that would be advisable.

The question came about when she saw me disconnecting cables from my solid state amp and connecting the cables from my tube amp. (both were off of course). She asked me why it wouldn’t be ok and I started babbling that the signal from one amp would then travel through the other set of connected cables into the amp that was not in use. Even if the other amp was off that could be problematic. If the other amp happened to be on then it could prove catastrophic for both amps and potentially cause an electrical fire.

What is the correct answer fellow audiogon members? Ralph?
ghasley
ghasley,

I know you are just raising a hypothetical question of what would happen. However, since you seem to have occasion to swap amps, you might find it more convenient to do as imhififan suggested and get yourself a Beresford Switch. They make several kinds. I have one specifically made to swap between my tubed mono blocks and my SS amp to a single pair of speakers. Just make sure amps are off when to throw the selector switch.

J.Chip

Hmmm, she may be thinking it’s time to ‘downsize or declutter’. Proceed with caution or an ‘I don’t know’
@b_limo

That is one of the few units I custom built for my friend to demo amplifiers in his shop for his customers and his audio club.
His customers usually don't had time to wait an hours or two for setting up and compare tube amps, so these selectors can switch between amps, while one amp is playing the other amp still on with dummy load connected, it is the best compromise we can think of.

No offense intended to anyone but Im not looking for a way to switch between the amps. It isnt hard to switch cables at the speakers. I have two sets of transparent gen5 speaker cables, one optimized for the tube amp and one for the solid state. Im looking for an educated explanation of what would happen. Sparks, blown caps, transformers? I appreciate @oldhvymec explaining what happened. Other explanations welcome but im not looking for a switch. Peace and thanks.