SATNAV upgrade

[Scarletpimpernel]

Few previous posts on here as well.
The below is what I fitted.

Sat nav unit 2014 series 3.75 MX5

hello Sorry couldn’t seem to find a topic area to cover this I have a series 3.75 MX5 2014 with the sat nav touch screen. It woks fine but the FM radio and bluetooth sound quality is awful! it sounds like it has speakers that cost £2 each!. I have improved it a bit by playing with the balance and fade settings but I cant find anywhere where i can actual adjust the bass and treble. any ideas? I dont really want to look at changing it regards chris