WJ,
You'll love the sound of those Italian bellas. They are a lot smoother though lack a wee bit in mid bass but quite sure your JL's shud take care of that. The aim of a well set up SQ system is all about reproduction of music in the most natural way ... glad you've found it in your system. Plus, the E39 is an excellent ICE platform due to its inherent low levels of NVH and superbly built cabin.
Hardly surprising since one of the best ICE system that I have heard is also found in certain 540i down in SIN. Naka CD700 MKII HU, Audio Control EQT, Scanspeak Revelator mids and tweets, SEAS Lotus sub, a pair of Brax GE amps and MIT cables / wires all round provide true sonic bliss.
erica34 ... between the W7 and your IDMax, most folks that I know wud opt for the IDs. The W7 has a reputation for being hard to set up and sounding rather boomy. The IDs are a better best for SQ systems in my opinion.
P/S - WJ, for proper justice to be done, the stock HU has to go mate. You'll be surprised what further improvements a good quality HU will bring into your system.
Cheers.