I'm curious what the difference is between regular bookshelf speakers (M22's and VP150) placed in cabinets, verses buying their in cabinet counterparts?

I am about to build my entertainment center and I currently own bookshelf M22's and a VP150. I need to know if I should get the in cabinet speakers instead.

Any thoughts?

Harman/Kardon DPR-2005 | SVS PB12-ISD | M22s | QS4s | M2s | VP-150