Looking for Power amplifiers with built in A/B speaker switches

usually, the 2nd pair of speaker terminals is limited to avoid any low impedances, so you might be smarter to find a Niles Speaker Selector, and that lets you have far more options choosing an amp,

 

@elliottbnewcombjr  - If you are saying there is protection circuitry in the B speaker terminals, I've literally never seen this.. I don't think the Niles switch is a bad idea, but I have never seen a single amp or integrated amp with both A/B speaker switches and extra protection or limits on the second. 

It's usually more like a a label that says something like: "Minimum 4 Ohms if 1 pair, 8 if two" 

If you think this is "usual" could you post a link to a couple of amps with this feature? 

Thanks for the input. I have never heard of a limit in impedances between A/B speakers posts. I'm never going to be operating all 4 speakers at the same time. I would think this being a switch it would 100% isolate the other set of speakers from the amplifier. I understand the amplifier itself has limits on impedances but that why I'm looking for a high current amp that can handle these loads.

Integrated amps often give you the choice of A, B or A+B.  So long as impedances are high and/or volume is low you are OK. 

Note that this isn't like a breaker/AC circuit exactly.  That is, if you keep the volume down you should be able to do A_+B, and if you turn the volume down while switching you will be OK. 

I'm looking at a Power amp, not an integrated. Also a speaker switch is either open or closed in the scenario I'm describing to at least one set of speakers. If I select A or B it should only see the nominal 4 ohm load of the one set of speakers I own. I have no interest in a A+B selection. I just want to select between speakers A or B only. Technically impedances in this scenario shouldn't be an issue if the amp can handle the load. Am I misunderstanding something here? I'm not sure what you are talking about. I know power amps having this capability are usually rare and you mainly see this option in receivers and integrated amps and that's why I'm asking about what other brand of power amps might offer this if any. Thanks

I guess I worded it incorrectly, but most warn about no 4 ohms if two pairs are connected. You can be careful, but someone else could operate it.

perhaps buy a Tandberg TR2080 (I miss mine) or TR2075, 3 sets of speakers, each can be as low as 4 ohms

https://i.ebayimg.com/images/g/IJkAAeSwK5FpHIPT/s-l1600.webp