I used to do the custom stereo thing 15-20 years ago. Strip out the interior, fit dynamat, couple of subs in the trunk components up front, all running off amps under Perspex floors etc.
But as car makers offered better systems, especially at the premium end I haven’t bothered as it’s not enough improvement these days vs the work involved, especially on highly integrated vehicles now.
I had a great Bowers Wilkins system In my Jaguar, and I would have ordered the upgraded B&W system in the XC90 had I gone that route, which sounds way better than the Meridian Surround system in the Disco, but it’s hardly a fair comparison as the Volvo system is a very expensive option whereas the Meridian is cheap.
But the Meridian Surround is good enough, although I highly recommend leaving it on the Meridian setting and making only small adjustments to bass and treble etc. depending what music you listen to it can sound very good, extremely clear, but if you’re into bass heavy hip hop or something like that then not so much.

 

Does the buzzing happen all the time with all sources?

Maybe not your case but...

I had the HK upgraded system in an older 2000MY that constantly buzzed the door panels and I tracked it down to custom cd's or streamed music that were mp3 format that would often bunch up some lower frequencies and cause the issue. Playing the same tracks as .flac never caused the problem.

 

Only buzzes once in a while. Only source tested was XM radio or FM. Didn't try CD or other input. Funny, I know there's a CD player installed behind the flip open screen but I sure never use it.

 

There is?

I'll have to go look . . .

 

I had to look to make sure I was telling the truth.

 

I only have like 400 CDs.