dying alternator?

alright, so im jammin to some music today, and the cd player cuts out, as in completely turns off, then turns back on and starts playin again like it does when I have a dead battery. I look over at the gauge and its on like 10 volts, way below normal. Now, I get home and start playin with it, and notice that if i just run headlights and stereo its fine, but anymore than that, and the gauge starts slowly dropping. Now, when the stereo cut out, i was runnin wipers front and rear, headlights(aftermarket high wattage, see sig), rear defroster, front defroster which means elec. fan is on also, and I had my stereo pretty loud, which consists of a kenwood head unit, 4 aftermarket speakers, and a 12" Kappa Perfect pushed by 400 watts RMS. So basically I had everything on that could be on. with all that on, the gauge would slowly creep from normal 14 volts down to 10 at idle, if i revved it up, it would take it back to 13 volts. Now, i just put in a new duralast about midsummer, but my alternator is still stock with 173k on the clock. I have also upgraded all major electrical sytem wires to 1/0 gauge, so wires arent a problem. So is this a dying alternator? My guess is yes, but just wanted to get some other opinions. Also, I heard ZJ alt. put out a little more amperage, so do dakotas. Any more info on that? thanks for all your help guys.