Nothing stands still.
Sue has already found an inexpensive solution to the lack of music in the Plus 4, while I quite enjoyed listening to the pure mechanical backdrop sans music, I knew it would be short lived. We have a blue tooth JBL Flipessential2 speaker coupled to her phone with the speaker placed in the small glove box opening (creating a sound box effect )and now we have both radio and pre-recorded music. We will get a double USB adaptor for the cigarette lighter socket to keep the phone and JBL speaker charged on longer trips. For the money the JBL speaker has a very rich and deep range of surround sound and much better than any sound I've experienced out of standard trad speaker setup. Whilst the speaker is facing you in the glovebox the sound also appears to be coming from behind you as well. Great value speaker for £75, we often use it whilst watching TV saves having a TV soundbar. Need to get a cradle for her phone so I can see the directions when we use it as a sat nav.
So I have a 1965 Plus 4 - and much like you, was using a small bluetooth speaker (UE Megaboom) for music. I mounted mine under the dash using a custom 3D printed bracket, and around town at low speeds with the top down, windscreen up, I enjoyed some fine tunes...
HOWEVER, I really like driving with the windscreen folded down (my car was fitted by the PO with an aftermarket fold-down windscreen). With the windscreen down, the wind noise was too much for me to hear any music...I have not yet fitted my brooklands screens - not sure if they will help...
SO...I went and bought a UE HYPERBOOM - which is BIG and fixed it to the passenger seat with bungee cords secured to the seat belt mounts on the floor. Looks a tad stupid, and I obviously can't take a passenger (but my wife doesn't love driving in the MOG with me...hair issues!), however this thing is loud enough that I can hear the music with the Windscreen folded...
