.01 uF Caps
JBL was big on the bypass capacitors, which is a source of debate here. What's not up for debate is how cheap one would have to be not to replace a 99 cent capacitor while you've got everything all torn apart. It's easy enough to measure for capacitance, but as Zonker once pointed out to me, it's quite a big deal to measure the increased Equivalent Series Resistance that caps get over time.
That 99 cents buys you a Dayton Film and Foil (regarded as the thing for bypass caps) capacitor. 12 bucks for both is pretty cheap peace of mind. If you need to skimp to save a few bucks, do it in the low-pass woofer leg of the circuit. Woof benefits least from having nice big polypropylene capacitors. Non-polarized electrolytics cost a small fraction as much.
The AMT's in the avatar sounded fine, but I regarded the caps like tires on an old vehicle - a wear item that would need replacing after 40 years even if Grandma rarely drove the car. My hunch paid off as the difference was immediately noticeable. I'm not sure if it had to do with the replacement or upgrade from electrolytic to polypropylene. I know amounts are relative, but it was worth the $150 (replace banana terminal, fuse holder and added a Speak-On connector as well) to my ear.