I took delivery of some old Heresy H700s last week and the treble had a noticeable buzz to it. I figured maybe a bad tweeter horn so I cranked my SET amp up to perhaps nine ear spliting watts to force the issue. Instead of smoke and screeching mayhem I found the speakers seemed to have cleared up little by little. I speculate they have seldom been pushed beyond modest volume and maybe I "blew out" the carbon! So to speak. I had a car like that once. The speakers sound pretty clean to me now. I also ordered a low power sub-woofer and a Schiit four band tone control. Mostly I stream Tidal hires through bluetooth 5.0. Does anyone have thoughts on "exercising" such old equipment? I hear a big difference in my speakers.