I own an MC402 with the c2300 (tube). I can't imagine it sounding "harsh in the mids to highs" with anything. I had the harsh highs problem for years and the 402 solved that problem. The majority of my recordings sound very good on it. I've run my DAC straight into the 402 as well with no harshness there.
I run the MCs on Aerial 7Bs - not the most efficient speaker at 86 dB spl. I wouldn't go any less power if the Thiels are in that range.
Lastly IMO and IME, if you're worried about harsh highs you should run not walk away from Thiels.
I run the MCs on Aerial 7Bs - not the most efficient speaker at 86 dB spl. I wouldn't go any less power if the Thiels are in that range.
Lastly IMO and IME, if you're worried about harsh highs you should run not walk away from Thiels.