What is RMS Power Bandwith, and how will it affect my sound system?

Question

I was looking at the Pioneer DEH-1900MP. Here are the specs:

http://www.crutchfield.com/S-Qp0OBI1u2to/cgi-bin/ProdView.asp?g=300&tab=features_and_specs&i=130DEH1900#Tab

I noticed that for most stereos, the RMS Power Bandwith ranges from 20-20kHz, but for this Pioneer it ranges from 50-15kHz.

However, take a look at this excerpt from the manual:
http://img96.imageshack.us/img96/3751/deh1900cf5.jpg

Under audio, it says the 50-15khz, but then under each specific function it has another set of numbers.

Basically, I'm asking if this stereo will be able to replicate low notes around 20Hz. Im using this in conjunction with an amp and two subs, and I obviously do not want to eliminate the 20-50Hz frequency range. Am I misinterpreting what Crutchfield is saying?

Answer 1

The stereo itself will produce it's RMS wattage in those frequency ranges. So if you just hooked your subs straight up to the stereo, you wouldn't get full power under 50Hz.

Now, if you hook up an amp with RCA cables connected to the pre-outs on the back of the head unit, you bypass that completely and then the RMS power bandwidth will be 100% determined by the amp. (and the sub, to some extent)