I had a look at the speakers provided by MMC. VDO HSP 1021 seemm to be an Eastern European brand from the mid 2000s and there is nothing about them in English on the web. VDO are not recognised as a supplier of in car entertainment, but are known in the boat world....
So, replacing them with a good quality Pioneer unit, such as Pioneer TS-A1723I units at about $65 a pair is a good starting point. There are probably another pair in the footwells. Replace these too.
I'd also replace the head unit with an Alpine unit.
The only problem with all aeros seems to be the antenna. Morgan have fitted an amplified "hidden" unit and it isn't very good. Replacing this needs a car audio specialist, especially if you are not very experienced.
Good luck...
