The "base" sound system depends also on the market. I don't have the details here right now, but in Germany and Europe at least there are three levels:
- Base, no subwoofer, no separate amplifier (uses radio for amplification), I believe 8 speakers if my memory doesn't fail me
- Audi Sound System (I guess widely believed to be a Bose?) with subwoofer (with separately adjustable level) and extra amplifier in the trunk, ten speakers if I remember right, 150Wattish
- B&O, 500+Wattish, subwoofer (not separately adjustable level), surround sound, microphone-based equalizing, most speakers
Sorry for not having exact numbers, going from memory here.
In addition whether or not your car has navi, it will have a slightly different amplifiers (and cars without navi will have slightly different/lesser audio level controls) but the above equipment levels are the same with or without navi. See the MMI article in my signature for explanation.
I'm not sure, but I guess U.S. Market has the middle level standard?
The lowest level is reportedly quite poor. The middle one is perhaps bass-richer than B&O (unbalancedly so, but some like it that way) and quite good value for money. B&O is the most balanced and arguably the best, especially if you value quality of sound over thumping bass, but many have lamented its subwoofer performance and lack of separate subwoofer level control. B&O front-speakers do produce good bass thoug, according to reports.
I agree. If you car has the middle level setup, I doubt you have anything to worry. It is good value for money and has some plus sides over B&O too (subwoofer levels and its controls).
One more note: B&O also has B&O labels and metal rings around the speakers, other sound systems have regular dash coloured speaker covers.