Here's a little secret sorta, the stock woofers are a little on the cheesy side, replacement woofers are very difficult to find for 2 reasons, the first being the small sealed volume of the enclosure, the 2nd being the magnet clearance in relation to the midbass enclosure. I think this palyed a key role in why they chose the woofer they did.
The stock woofer has a plastic "beauty ring" that i've removed and successfully used as a shim to make this woofer
http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=290-325
work without any further modifications.
EDIT: a few notes for anyone electing to go the replacement woofer route. 1. the internal wiring spade connectors are crapola, expect to break and replace a few. 2. care and persistance will be required to remove the beauty rings from the stock woofers, i did it which means most anybody can. 3. be sure to use some silicone or similar quality sealant bewteen the beauty ring and new woofer, and beauty ring/cabinet especially around the screw holes, these speakers MUST BE AIRTIGHT!
............... and recap the XO's, the 165mfd electrolytics are for the hi pass filter and can be replaced with equivalent electrolytics, the ones i've replaced had drifted enough to raise the knee point of the HP filter to over 60hz. Replace the series caps with good quality film/foil or metal/poly caps to really hear how "invisible" these speakers can be.
The difference between the cost of refoaming and replacing the woofers was quite negligible, especially after hearing them.
PS-10's are IMO, definitely under appreciated, and often under the radar in price, hands down my favorite small speaker.
They really don't need a sub for most applications, but they are internally hi pass filtered at 40hz so a sub will be a must for those of you requiring sub 40 hz response.
Just my .02 y'all understand.....................