I have a Bose Soundlink that is pretty darned good but you probably want something bigger. Depending on how big, Altec makes a good one, I saw it in person at Sams Club. I think this is the one I saw:
https://www.samsclub.com/p/altec-lan...lp_product_1_1
Sony makes some good ones too, if you have a Best Buy nearby then you can listen to them in person. It's a tradeoff. Good sound, Loud sound, cheap price and Small Package are hard to come by. If it were me, I'd look at the Bose. The Bose is still cheaper than buying speakers, wiring kit and stereo. Just my $0.02