Greetings!

First a bit of background. I'm 22 and my family owns a small vineyard where I can throw parties and hang out with my friends.

We listen to everything there from rock/metal to rap and techno depending on the squad's preferences that is there hanging out.

Currently I have a 2.1 50W amplifier board from ebay there powering my dads old Magnat speakers and a Subwoofer from sony's home theatre.

It's ok the way it sounds for the aplication but when you want to turn it up all the way it starts cutting out (probably the power supply's fault) and the sound quality isn't greatest and it lacks volume.

Would an old 90's stereo amplifier like Sony F319R 
(https://www.hifiengine.com/manual_library/sony/ta-f319r.shtml) or something similar that goes for around 50USD used locally make sense to buy? I was thinking of buying a separate amplifier board just for the bass and running either a y splitter or powering it trough a low pass crossover/filter from the B side speaker out.

Or would again an all in one 2.1 board from ebay make more sense?

So I would like to upgrade the existing setup but I'm not totally sure witch route to take. My budget is around 75USD and I wouldn't like to go much more.

Every suggestion is welcome and feel free to ask questions.

Thanks, Sven.