
soundcore
Boom 2
Loud, bassy beast; needs EQ, no aux.

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I used to have a bluetooth speaker too, although it was a JBL GO 2 so definitely smaller than yours. I had it attached with a stem mount by SP Connect and it was sturdy enough, maybe that's the right thing for you if you would consider getting also a smaller speaker. Nowadays I travel with one BT earphone in my right ear and I suggest you either that or the bone conducting speakers, if you're open for alternatives.
JBL GO 2 has a jack in, internal battery and it's cheap. I will try it with my modular synth and let you know how it works.
As someone who's replaced the battery of my beloved 9 yr old Flip 3 (still working), my advice is the same as the others: get a new one. I've had 2 JBL Go 1s, and 1 Go 2. That static is probably from a cracked rubber ring around the speaker cone. You can open up the Go 2 and repair that with tape, but at this stage it will just crack again at another place. Replacing the driver/cone is too much of a hassle. In my experience, a JBL Go lasts 4-5 yrs. So yours has had a great run.
JBL go. I have 2nd gen, it's very nice.
I see you don't like any bass/mid thump? But need a clear sounding one? Look for JBL go 1 or 2 those models really have little to no bass at all but sounds really clear. Latest iteration of them sounds fuller and better but for your needs and wants I'm sure it will not satisfy you.
The best I’ve had is the Sony SRS-X5. But I should also admit I haven’t needed to shop for Bluetooth speakers since I’ve bought it 8+ years ago, so I have no idea really. I do have a UE Roll and a JBL Go and Go 2, but they aren’t comparable. They are in a different class altogether.

soundcore
Boom 2
Loud, bassy beast; needs EQ, no aux.

Bose
SoundLink Flex Series
Durable, compact, good for size; distorts at high volume.

Minirig
Minirig 4
Unrivaled sound, long battery; pricey, flaky Bluetooth.

soundcore
Motion+
Best value, excellent sound with EQ; needs EQ.

JBL
Charge 6
Durable, portable, clear bass; dull vocals, distorts up close.

Ranked #1
Anker - Select 4 Go

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Harman Kardon - Go + Play 3

Ranked #1
LG Electronics - XBOOM Grab

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soundcore - Boom 3i

Ranked #1
JBL - Boombox 4

Ranked #1
Anker - Select 4 Go