I have an old pair of 40 watt Pioneer speakers that came with a stereo system I got as a gift many years ago. I want to use them as the rears in my new 5.1 setup but they have a proprietary plug attached to them. I’ve uploaded a pic here. It looks like ordinary speaker cable and my guess is that they would work if I just cut the plug off and wired them up to my amp normally. But before I possibly ruin my amp and/or the speakers I thought it best to run it by someone. What do yall think?
I’d go with "cut em’.
>>>> Make sure the speakers don’t have built in amps of their own!
These speakers don’t have some internal power source, do they? I haven’t seen a plug like that before on a speaker. Does the other end of this disappear into the box, or does it hook up to banana plugs or some other “normal” speaker hookup? If it hooks up externally to the speaker, it is most likely just a fancy plug on regular wire.
You may to eyeball the socket on the old stereo these plugged into and see if it gives you a clue as to output of the socket. I doubt that the speakers have their own power source, like a sub-woofer, as they would be heavy and expensive.
Chop, chop!
A Gay Bishop? Can’t beat that!
That’s what I was getting at - sometimes those plugs provide power to the speakers internal amp(s).
The wire just disapears into the box, but I don’t think the speakers have amps built in. Pioneer possibly just added their own plugs and jacks for ease of use. Here goes nothing… I’ll let you know if it works or if not.
Success! Now the only question is how badly will the sound be affected when I splice longer speaker wire onto them…
Thanks for your help guys.
You should be fine.
I wonder if that plug was to insure that you buy a Pioneer amp or something.
The only appropriate answer to this is “Duh, Becky!” 
Guessing by the skinny wires, the funny plug is there only to make speaker installation goof-proof and prevent you from using any other speakers.
As for affecting the sound by splicing in more wire, as long as you’re not planning to add in 200 feet of wire, you’ll be fine with regular lamp cord from the hardware store. Just be sure the connections are good - if you can, solder the splices - and well taped so nothing shorts out.
One other thing, watch your phasing, no harm done if its off, but it can muddle the sound.