I have seen a few posts recently about Head units with digital inputs or room/car correction.

To create one of the best sounding installs within a car enviroment I would reccomend the following is evaluated.
Ideally this would be used with the empeg digital output to eliminate any souce based noise pickup and some focal or other high end speakers and amps. At around 450 British pounds (approx 600$ ) its a absolute steal...


Alpine pxa-h700
the PXA-H700 delivers state-of-the-art vehicle sound tuning with 1/3 octave equalization, digital crossover and precise digital time alignment.

Utilizing Alpine’s exclusive MDAC 96KHZ/24 Bit multi-level digital-to-analog conversion technology co-developed with Burr Brown, the PXA-H700 delivers ultra-high quality sonic performance with precision sound tuning directly from the head unit. The PXA-H700 features 8-channel digital time correction to precisely align all speakers for maximum sound imaging; a digital equalizer that offers up to 165 bands of 1/3 octave equalization or 27 bands of parametric equalization; and an 8-channel digital crossover with variable slope adjustment and crossover points to deliver phase-shift free performance for any multiple amplifier system. In addition, the PXA-H700 features Alpine’s own Media Xpander™ sound correction technology for enhanced audio quality from compressed media formats.

http://ecominet2.alpine-usa.com/pls/admn/item_info?p_item_name=PXA-H700&p_category=160&p_subcategory=&p_main=10