Tell me more about this Amplifier and what phase correction is please.
So basically, various companies do car amplifiers.
One such company is Bimmertech. They don't make theirs, however. They buy and rebrand Audiotec Fischer products:
https://www.audiotec-fischer.de/
Their amplifiers, some of which are designed to be drop-in replacements for the HK version, have digital signal processing and pretty comprehensive software, giving you control over phase, time alignment and EQ.
I did this in my 135i, which has the HiFi upgrade (HK equivalent for that model year) and it transformed the sound.
Audiotech Fischer even have some pre calibrated files, so all you'd need to do is set speaker distance from your seating position and the speakers will be EQ'd.
Audiotec Match UP 10DSP as PnP Upgrade For HK Equipped Cars?
f80.bimmerpost.com