I think you're missing part of the reason the player was invented - the all-in-one-unit. No extra boxes, no long-distance wiring, no extra installation hassles.

For the security issue (which was the essence of the original post, IMO), I think there should be a 'secure' option where a relay-driven bolt pushes through the frame and into the chassis of the empeg unit itself. This could be a top-level menu option, with the 'unsecure' option being accessed by a PIN. An option with the security would be whether to allow play access and emplode access once secured - so that if someone really has ripped your car apart to get at your empeg unit, without the pin it's just a lump of componentry. (A master rolling-code override from the empeg boys would allow you to get around forgotten PIN woe).

(Aside: the internal serial number and owner information issues have already been covered in another thread.)

For the rest - why have it anywhere else? The unit already packs a heap of power into a standard sized unit - any larger and you'll be just limiting the market.

When I get one it's going to take pride of place in my car, dammit!

Save the whales. Feed the hungry. Free the mallocs.