I am considering a pair of of AR-11 speakers. The owner replaced the foam surrounds with a set of rubber surrounds (which he says were provided by SimplySpeakers). The work appears to have been done well, but I am concerned about the effect this change will have had on the performance of these woofers. To my ears, they seem to have less low-end output and impact. I assume that this might be an effect of the rubber surrounds being stiffer, less compliant than the originals? What would be the expected effects of the switch to rubber surrounds? If I end up getting these speakers, I will probably replace the rubber surrounds. Is there a best source for surrounds that are closest in performance to the originals? Also, I noted that there is a layer of some sort of masonite or similar material between the frame and the surround. I assume that this is original? As regards the tweeters...they appear to be original, and they sound good to me, but the dome is a cream/off-white color. In all of the AR-11 pics I've found, it is black. Are these perhaps early versions, or could they potentially be aftermarket replacements? Thanks for any advice/assistance.