I'm gradually replacing my 20-year-old system as bits of it fail. Earlier in the year I got the Marantz CD6005, which sounded great through my old Marantz PM57 amp and JPW ML510 speakers. But then the amp blew and I bought the PM5005 to replace it. I hooked everything up and had the feeling it didn't sound quite right. Playing around, I found that pushing the volume much beyond the 9 o'clock position or turning the bass up to full causes a really unpleasant distortion on the bass in both speakers. I'm sure the speakers were capable of handling those volumes from the old amp. Any ideas?