I too am a true believer in the HPM 100's. I bought mine new in about 1976 while stationed in Germany. I remember the first article in a a hifi magazine of the up and coming, but not released yet HPM 100. I could hardly wait until they were available for sale in Germany. I bought them at an Audio Club in Franfort. I still have these same speakers today. I have recapped them once sticking with close to stock parts. They sound great. I also experimented with a crossover mod designed by a well known AKer, but didn't seemed to be that impressed, so went back with recapped components. IMHO, unless you have a large listening area, be easy on the mid level pots. I find 0- maybe 1 1/2 work good. Get the up slightly off the floor, slightly tilted back and just barely angled in towards the listener. With a good clear recording, you'll swear you are right there. Now that y'all have heard me preach, back in 75 or 76 when the brochures and adds went out, there were talk from I believe Pioneer, that these speakers would be mirror imaged. Meaning a left speaker config and a right speaker config. Mine were apparently not. They are both the same. However on at at least some of old brochures Pioneer shows the speaker with the attenuators pad on the left. Both of mine and every other one I've seen the ATT pads or on the right side facing the speaker. Any of you know any thing about that? In fact I'll try to attach the brochure here. You'll see in the brochure that the ATT is above the super tweeter. On mine and every other one I seen the ATTs are above the round tweeter. Just wondering.
http://akdatabase.com/AKview/albums/userpics/10004/Pioneer HPM100 Brochure.pdf
Bubba57