Patio tunes

I have a Blu tooth Marshal medium size,  take it on camping trips, Get together s and hotel conventions,  Sounds really good, as long as the source is good it plays loud with good quality, separate bass and treble knobs to. 

I'm not sure of your situation, but I'd assume that you're looking for a best balance of performance, cost, and convenience.

Ideally, you'll have a system you don't have to transport in & out, or set up/tear down.  IF you have the ability to get speaker wire from ANY protected space (with AC power) to an area that would provide decent speaker placement and then connect to an amp, this would be ideal.  I have found that amps can be pretty rugged and survive temperatures from zero to one hundred degrees if they don't get wet.  I have one in a garage in one home, and in a storage shed in a boat house at another.  Both have been in service for years, with no issues.  

Streaming via tablet or phone is a good use of resources, but unless you have a dedicated phone/tablet, you're music will likely be interrupted with texts, alerts, phone calls, etc.  It's best to find an amp with apps on board with access to popular music services -- including your hard drive, and use your phone/tablet for control only.  I just checked and found some good used examples on eBay for $129 that meet the above criteria.  

Good luck!

Have you considered any of the really small but powerful Fosi Audio options? I recently purchased the BT30D to drive some well worn and weathered Sonance in ceilings and I am amazed at the power along with separate tone and sub controls. After years of always wondering I also added the Dayton 10IP66 outdoor sub for some low thump and the whole combo actually sounds great!

There is an even better pro model out now as well.

Amazon.com: Fosi Audio BT30D Bluetooth 5.0 Stereo Audio Receiver Amplifier 2.1 Channel Mini Hi-Fi Class D Integrated Amp 50 Watt x2+100 Watt for Home Outdoor Passive Speakers/Subwoofer Powered Subwoofer : Electronics

check out the JBL BoomBox 2....it's on sale at you know where  300 bucks