Looking for a new amplifier...Again.

I've been listening to numerous amps again on loan and near the top of my list of must listen-to-in-my-home amps is a Viola stereo amp. The mono's are to rich for my blood right now.

My question is that I've seen more Viola's on the used market lately and would be very interested to know what amp(s) these owners are moving up to. My thought is the next level Viola but not in every case.

If you are a previous Viola owner, what did you move up to?
If you feel the need to keep upgrading your amp, maybe there's an issue somewhere else in your system.