Just try to call Conrad Johnson and ask them about some of thier older units like the MV-75 or Premier 1, and NO one will know anything about it , nor will they have any interest in assisting you .
ARC, on the other hand, SUPPORTS all products they have made since the SP-1. Try to find this from the many mfrs out there.......Maybe Bryston, maybe Madrigal, heck many companys are not in business anymore.
Before you part with big money, be sure the company will support you.