So I have a vintage Pioneer SX-450 Amplifier, basically just like the one in this ad: https://www.etsy.com/listing/1018874087/pioneer-sx-450-receiver-works-needs
It has a phono-in, and multichannel out stereo speaker hookups (A, B, A&B)
I have it wired all over the house. It is an old house, and I repurposed a lot of existing wired connections to play the sound in multiple rooms.
However, for a while now, the left stereo channel doesn't play, and the sound is out in most of the rooms. Sometimes if I turn the sound way up, a connection will suddenly jump back to life.
I was going to just replace it, until I found out how much getting another setup with the same functionality would cost! So I disconnected everything, and reconnected it. When I turned it back on, everything worked perfectly! I was so thrilled, I got a speaker splitter, and put my different rooms on different subchannels. It all sounded great.
It worked for a short while. Now, a month or so later, it's worse than ever.
But it occurred to me it might not be my amp, it might be my bootleg wiring. I don't know anything about impedances or anything, I just wired up everything with the wires I had on hand.
Is that likely to be my problem? And how should I fix it?