I am selling my beloved 500. It has been extensively modded by Musical Concepts in 2006. It is a signature version which includes John's best upgrade sans the Jensen power supply. It has the TP-500 twin toroid transformers and is completely dual mono.
Condition is perfect. All internal parts were replaced with new parts in '06 and I bought an "as new" cover and face plate in 2010. The only original Hafler part is the chassis and there are no issues there either.
I would be open to specific trades for speakers... KEF 107's, NHT 3.3's, Meadowlark Heron's, or Magnepan Tympani's