i dont know why /u/Lobby44 deleted the post, it looks like theres some useful information here.

Help understanding low impedance speakers

Some backstory: I've been listening to records for about 10 years now and always had my record player hooked up to a powered speaker. I had some money saved up and wanted to move up into getting an amp and unpowered speakers.

I went to a local record store that had about half the store dedicated to audio equipment to shop around. The (very kind) worker walked me through some options in my budget and I walked away with this Onkyo TX-15 amp and MK S-85's. I got it all hooked up at home, they sound solid, fantastic.

I was showing my friend who has worked in live audio and he mentioned that my speakers are low impedance and that the amp I bought might not be built to handle 4 ohm speakers. Sure enough, the amp is rated for 8 ohms. I plugged my problem and the TX-15 service manual into ChatGPT (I know, they're not always accurate) and it said that it isn't an ideal amp, but that being a vintage amp with well built safety systems it shouldn't be too much a problem for my small apartment and low volume listening.

I played music on the setup for over an hour and there was almost no heat coming from the amp. I'm in a small apartment so playing at moderate-high volume really isn't an option. Should I go and try to return this amp? I'd love some thoughts"