Can you use different amp makes to the head unit make? (like home HiFi) or
is it like the CD changer and H/U needing same control logic?

If same what Sony amp for sound quality?

If any what £50 - £150 again for sound quality - H/U is 4x30W RMS, want 2x50
to 2x80 for the door speakers which will be Infinty 605CS.

Thanks