[aschen]

looks like a passive subwoofer that probably has the amp built into the old reciever. This is not customary. You can use something like this if you want https://www.amazon.com/Nobsound-Hi-Fi-Subwoofer-Channel-Amplifier/dp/B08D6G9CB7/ref=sr_1_2?crid=17GD5JBQU5713&keywords=subwoofer+amplifier+home+audio&qid=1666289904&qu=eyJxc2MiOiI1Ljc4IiwicXNhIjoiNC43NSIsInFzcCI6IjM uNjgifQ%3D%3D&sprefix=subwoofer+ampli%2Caps%2C103&sr=8-2&ufe=app_do%3Aamzn1.fos.18ed3cb5-28d5-4975-8bc7-93deae8f9840

it is a chipamp so its not really 300w but is probably plenty.


I would be more inclined to just spend a bit more on an actual decent powerd sub however:

even this super cheap monoprice unit is probably better than the rca one and would hook right up to your receiver
https://www.amazon.com/Monoprice-108248-60-Watt-Powered-Subwoofer/dp/B009GUTJ34/ref=sr_1_2?crid=348W469MZIGAF&keywords=powered+subwoofer&qid=1666290175&qu=eyJxc2MiOiI2Ljc3IiwicXNhIjoiNi4wOSIsInFzcCI6IjQ uNzUifQ%3D%3D&sprefix=powered+subwoofer%2Caps%2C114&sr=8-2

people like these cheap klipsch as well which will be like 10x better than what you had I would think

https://www.amazon.com/Klipsch-Reference-R-10SW-Powered-Subwoofer/dp/B00MH42BBI/ref=sr_1_1?crid=348W469MZIGAF&keywords=powered+subwoofer&qid=1666290292&qu=eyJxc2MiOiI2Ljc3IiwicXNhIjoiNi4wOSIsInFzcCI6IjQ uNzUifQ%3D%3D&sprefix=powered+subwoofer%2Caps%2C114&sr=8-1&ufe=app_do%3Aamzn1.fos.18ed3cb5-28d5-4975-8bc7-93deae8f9840