I have talked with an engineer friend of mine (Masters degree in electronics engineering) on this subject, and he convinced me that I gave out some misinformation. The misinformation is that a polarized capacitor can be used as an AC, (i.e., music) filter element. I had incorrectly assumed that because audio amplifiers do not have a DC offset at their outputs, and that the average value of sinusoidal AC is zero, then using a polarized cap is ok. The fact is that because the AC signal does spend an equivalent time on the positive side as well as the negative side of ground, the capacitor will see a reverse voltage for half of the signal, regardless of the fact that the average value is zero.

I will say, however, that I have done this mod on both of my Crossfire's with no apparent change in sound quality, which would be an indirect method of determining if the electrolytic capacitors are ok or not. My feeling is that because I only occasionally crank up the volume to real loud volumes, the average AC signal voltage is low enough to not blow the capacitor. Here is an example: The average wattage at mild volume levels are probably around 1 watt, and 1 watt rms (average) into a speaker (4 ohms) calculates to a rms voltage of 2 volts. I am speculating here, but maybe this just isn't enough reverse bias voltage to blow the cap. What would probably happen if the caps started to fail is that they would become leaky on the reverse bias side of the AC signal and begin to "rectify" the AC signal…basically as the capacitor starting going bad, it would start to appear non-linear on the reverse biased side of the signal at the lower frequencies and would probably sound like a distortion in the bass portion that the capacitor is supposed to filter out.

Regardless, I will have to state that only NON-polarized electrolytic caps should be used for this mod. The capacitors at Amazon.com that danimal recommended are ideal, and I am going to change mine as soon as I get a chance:

http://www.amazon.com/gp/search/ref=...0&Go.y=0&Go=Go

Amazon stocks a good variety of values of non-polarized caps: 120, 150, 200, 220, 250, 320, 330, and 400uF.

Sorry about the bad info...and really long post...good luck to all!