Thanks very much for your thoughtful response and suggestion. As it turns out, I stopped by Upscale Audio on my way home from work and talked with Joel and Kevin. I am going to buy an open box Prima Luna EVO 300 Integrated amp and make that my new "end game" amp. Upscale is going to take my pristine conditioned Musical Fidelity M5si amp in on trade and they are giving me a very fair deal to offset the price of the Prima Luna. I will make plug here for the team at Upscale. I really like doing business with them and I'm fortunate enough to live ten minutes from their store location.
Now I just need to explain to my wife why I must trade in, and up, from the M5si that I bought just 45 days ago.

