Who are they made by?

 

older ones had Harmon karmon and the newer ones are alpine

 

All X308's are fitted as standard with Alpine units.
Harm Kardon is specced for the upgrade 'Premium Sound' system which included parcel shelf woofer, upgraded amp and extra tweeters in the 'A' pillars.
They are avery reliable system and parts and servicing are still available from Alpine.

 

I know about the speakers and amps but who makes the head unit?

 

As I said before...ALPINE ;o)

 

And Alpine is the better and newer one, and has more Watts power.
And the DSP (digital sound processor) From all 1990 and up models I believe.
Standard in all Daimlers/Vandenplas´s´(USA)