So they are not oil-filled, which can last a long long time if they are sealed; and they do not 'dry out' which suggests they are not nonpolar electrolytics (NP's). The only remaining major type is film and foil or metallized film caps. I assume that is what is in there. Whether replacing them will change the 'klipsch sound' may be a matter of opinion. Without further info on what makes those old film caps so special, I can't say one way or the other. But I have seen even film caps drift out of spec and have increased ESR (Equivalent Series Resistance) which basically means they become more of a resistor than they should be, decreasing the output.