Need Opinions on the following

I am currently using a Primare I21 to drive my Thiel 1.6's. I am thinking about purchasing an Rotel or Adcom amp in 200 per side range.

The Question.

Which engineering is better Primare 75 by 2 or Rotel 200 by 2 or Adcom 200 x 2?

I want extra power but I am not sure if it will hurt or improve my sound.

All thoughts are appreciated.

Thank You,
great system...leave as is.
It depends on whether or not you're really stressing the I21. If you are, then just about anybody's amp unstressed will be an improvement. I side strongly about watts being much more important than brand name. If you operate an amp in its linear region of comfort, you'll be fine with just about any amp. Of course, just my 2 cents.

BTW, I'd pick at ATI AT2002 balanced amp over either of your listed choices. Another option I'd consider is the Parasound A21.
This is how I would come to a conclusion on this. Do I want the same sound just more loudness and authority? If so set a price range and research reviews. Look for something similar in sound and hope it interfaces like described in the reviews. But remember you need at least 200 watts to make a noticeable difference in loudness and authority From what I read of the reviews this amp (Primare I21)has a relaxed sound and some what diffused it lacks precision in both imaging and timing terms and it is not a tight sound. it could spread the sound wider than the speakers and do so in an effusive yet engaging fashion. There is a touch of exaggerated openness but this space allows notes to form a fuller image. Is this the kind of sound you have now? If not take into consideration what the Thiel 1.6's added or took away then try to mate a Amp. If it was me I would go with Parasound Halo A-21. See if someone has that set up and if it interfaced well.

Good Luck
The Primare should be smoother and have more meaningful detail(ie musical) than Rotel and Adcom. I think they would be a step back...