In the right rear wheel arch.
Sounds like you just enjoy installing stuff. Not all recordings are perfect but I don't buy for a second that the E-Pace needs new tweets and a gonzo meatball plexiglass box and new sub. I'm a musician, been using EQs since the 70s. I know what they can or cannot do. Occasionally, I buy a bad recording off iTunes that needs some cleaning up, usually a live recording. And not all studio recordings are superb. Bass and treble is a two-band EQ. Imagine what more bands can do. I don't need subsonic booms or earthquake-grade rumble inside my E-Pace. Nor do I rate sound quality on a Richter scale. No idea what you listen to but too much gangsta wappa hip-hop can do that to you.I don't know if the two Meridian systems use the same head unit. If they do, then it can be programmed. Coming from the BMW / Mini world, we could program just about everything with an OBDII module and an app called BimmerCode.
As far as an EQ fixing a bad recording, song by song, I don't buy that for a second. Having built over 30 audiophile car systems, once a tune is complete and plays a known source recording accurately, every song will sound as it was recorded. It's a set it and forget it thing. The Meridian 380 sounds OK, but needs some tweaking (a sub, better tweets to start) but will never be phenomenal....and I'm ok with that.