Needed: Honest Advice on high-end amps- either mono or stereo

@OP What specific advice are you looking for?

I happen to agree with Viridian. Audition, audition, audition. No one knows better than you what you like. And that really applies to pretty much everything. Sure, get some suggestions, ideas and general guidance, but at the end of the day... does the music you're hearing move you? Like most everything else, do what makes YOU happy.

@ghdprentice that question I quoted was from another member to which I responded with lightheartedness, but I appreciate the advice about Virtual Systems (which makes this forum unique). 

The diminishing returns is a real thing and if your budget can take it then its worth it to spend more to get a minimum upgrade. The thing is inside all these amps, regardless of price above a certain level, are similar components, there are only so many people making resistors, caps, transistors etc. It boils down to circuit design and the makers secret sauce as they say. Small changes really but worth it or not is up to the individual. 

You can't really ask the question about amps alone.  If you don't have, or don't plan to add, other components in your system that match the quality level then spending big $'s doesn't make sense.  However, there is not really a question whether a well-matched high-end system has better sound quality.  Whether it's a good value is a whole other question only the individual can answer.  The cost/benefit of moving up is more exponential than linear.  Same concept as why someone would buy a Porsche rather than a Chevrolet.  Relative value is subjective not objective.