I've experienced the 6922 tube failure that Gmorris mentioned (at locations V-7 and V-8). However, I do love the sound of this amp. That's why I'm curious about the sound of the upgrade. ARC has the technical info on the upgrade available as a fax (they're delaying, they say, posting to their website to coincide with other product introductions). The changes are as Ttl2000 says, which basically is the driver stage from the ARC VTM200-200W monoblock. BTW, I've also heard from an ARC dealer that 6922 failure was one thing that prompted the revision. However, what does this new version sound like? The guy I talked with at ARC said that the bass on the MkIII made the Mk II's bass response sound "wooly" by comparison. He also said that the new amp just sounds like a more powerful amp overall . But, what do less partisan ears think? America wants to know!
