Mills MRA two types of different brand ?

I cant comment on how the newer ones sound compared to the older ones made in the USA but I would not call the newer brown shinny ones slightly dull and warm. I replaced the sand resistors in my Dynaduio S 25,s with them and they do not sound dull and warm to me compared to how the s 25,s sounded before quite the contrary I would call them fast, detailed, tonally correct with alot more micro dynamics.

Actually your second questions ask how do they sound along with selectric talk about the sound. I was only trying to help excuse me.