This was a fun and challenging build!
Full gallery here.
I ordered some cheap single board amps and power supplies from AliExpress and used a DSP so each speaker (mid/tweet/sub) has their own dedicated amp and fine tune control ability for the frequency drop-offs, gain, etc.
They sound amazing!
If he enjoys electronics and music, then I definitely recommend encouraging his journey into this direction! I would be okay with you asking questions in this thread if you need any help/guidance/resources.