I play several instruments and am currently looking towards purchasing a digital piano with MIDI capability. Most of the digital pianos I am looking at require an external speaker system (such as a keyboard amp or PA).
From what I have seen, the price ranges are competitive for each (at least in the lower range). But, I'm cautious of the sound that each produce. Is it worth sacrificing the sound of a dedicated amp to a PA system (is there even a disscernable differance).
I was just curious as to what everyone thought of the pro's and con's of each (relative to price, of course).

I guess it depends what you mean by PA system. An amplifier is really not just an amplifier, but also a preamp and a speaker all built into one piece of gear. A PA system generally consists of those same components in separate pieces. An amplifier can have multiple channels (inputs) but usually not more than 6 or 8. A PA system's "preamp" comes in the form of a mixing board and usually has at least that many channels and can have 60 channels (or more). Technically it's possible to plug a microphone into an amplifier, but they're not generally designed for anything other than instruments. PA systems have multiple microphone preamps and are designed for any instrument. Typically PA systems are more expensive and have a greater potential for high quality sound. PA systems can also range in size from a small integrated system to the PA system at a concert arena. A PA system can range in price from a few hundred dollars to several hundred thousand dollars. But this is a very generic answer as PA systems can be good, bad, and everywhere in between (just like amplifiers). Amplifiers are usually a bit more portable and top out financially at around $1500. But you can get a decent one for a few hundred dollars.

Can you give us an idea of what you've looked at specifically?

I guess by PA, I mean a lower end portable system such as:
SoundTech C172
Kustom Profile System One
Audio Choice C120
As for equivilent (price wise) Keyboard amps, Ive looked into:
Roland KC60
Motion Sound KT80
Behringer KX1200
Many thanks for the great input, and excellent info provided.

Roland and Motion Sound make great amps. I'm not as thrilled with Behringer -- certainly a different level of quality/performance. I'd suspect that if your budget is "light" that you'll do better with an amp. Do you mind sharing what your budget is?

I'm still about 2 weeks from my planned purchase date. So my amp budget is still a bit sketchy, but currently it looks to be in the $400-500 (USD) range.

In that price range, you'll definitely be better off with an amplifier. I highly recommend the Roland KC300 if you think you might need a bit more volume than your living room requires. If not, the KC100 or even the KC60 will do nicely. As I said in an earlier post, Motion Sound makes great products as well.

IMO the tube channel of the Motion Sound KT 80 is an advantage.

To reach a similar goal I use a tube DAC/preamp for connecting a cd player and a digital piano with my active studio monitors (MEG RL 906).
The result is an almost realistic combination of the warm tube sound with the analytic studio sound.

If you haven't already made your purchase... I think you would do well to look for a used/demo Mackie powered PA speaker, or even a JBL EON. These are incredibly loud, super clean/accurate, and much more versatile than a keyboard amp in the long view, as they are also perfectly suited to stage monitor or mains usage. If you need to warm up the sound for your keys, do as another here has mentioned, and throw a cheap tube-preamp in front.

-Lorenzo

Actually, the Roland KC 300 keyboard amp is considerably more versatile than either the Mackie or the JBL. Don't get me wrong, the Mackie and the JBL are both fine products (I have several EON's). But neither are multichannel devices. The Roland KC 300 can accomodate 4 stereo keyboard inputs (or 8 mono), has a stereo link for adding another amp, and has a stand mount built in for mounting on ultimate support speaker stands. It also has a monitor input (which remains separate from the keyboard inputs) which allows it to be used as a stage monitor for vocals, guitars, etc. Both the Mackie and the JBL sound great, but are really intended for PA use.

Sounds like a great amp, Steve.

I guess it's all about emphasis. I don't think I like having a mixer built in to a speaker I'd like to use as mains on a small PA... but I guess you're still right - over all, a full-blown keyboard amp is probably more versatile.

-Lorenzo

I'm with you Lorenzo. But remember, the budget in question is in the $400-500 range.