Anyone heard Mastersound Amps?

"I'd like to get opinions on people who have heard them."

I have heard the amps but to answer your question, I have no opinions on people who have heard them. I don't know these people personally but everyone who heard the amps with me seemed nice enough.

I have a Mastersound/Vaic 300b SE integrated amplifier and love the beautiful SET sound. Unfortunately I cannot comment on your question with any comparison to other amps other than with my set-up I love this amp except for the bass. The low end is not as extended as I would like but the midrange clarity and the depth and focus are so well done I bought the amp in spite of my reservations about the bass. I have Reference 3a MM deCapo I speakers and a Cary CD-308, MMF-7 TT with Monlithic Sound phono stage.
There is a review of an Ayon amplifier in the Jan(?) issue of TAS and for that matter check out the Ayon website as Mastersound has merged with them.