plenty of higher end builds are being done w/o head units now, it's not all that ground breaking at this point. It's all iPods/iPhones & smartphones now. I plan on no h/u or a stock style dummy in my 67 since you will never see an aftermarket DIN chassis installed in a 1st gen that looks good due to the dash contour. I'd have to look around, I'll post if I see any.
increases line out voltage
http://mobile.jlaudio.com/products_c...hp?prod_id=446
isolated power supply to kill line noise:
http://www.davidnavone.com/cart.asp?14&pid=178
it seems iCrap often has noise issues using the main connector. plus auto electrical system don't always have the cleanest voltage. that site has interesting stuff on it.
the bluetooth idea is neat if it doesn't compress the sound even more than the mp3 or net feed already does.