Pass Labs XA-160 vs Levinson 33H

ARC recommends 20Kohm input impedance at least. My Pass is 22Kohms input impedance. Am I too close to the lower limit??? Would getting something with higher input impedance help? If so, in what ways can I expect a high input impedance to improve the sound?

Pbb,
I guess brains was a poor choice. I was quoting someone else. I suppose a better choice of words for the amp would be the muscles and nerve center. Bottom line is correct matching of amp and speakers taking into consideration room size and choice of music and headroom needed.

ARC recommended the same 20k for my old ARC pre-amp which had a 600 ohm output (I assume the same output as the Ref 3). Ran it with an old Threshold with a high input impedence and another anp with a 10k input impedence. The mismatch (I'm told - I've never actually heard the result of a mis-match) causes a rolloff in the highs which will be precieved as such and a consequential softening of the bass (FWIW the sound of 'tight bass' is IMHO more of a result of
the correct presence of the high frequencies in a drum when struck or a bass when plucked).

For myself, I wouldn't be concerned with an impedence mis-match on you present system. Too bad you can't try that system with tubes - then you will have something to really be concerned with that you will actually hear and not just fret about! :-)

newbee, thanks. I am actually trying to arrange a demo of the ARC Ref210 amps. Lets hope I dont like it!

Tboooe,
Have you considered auditioning a McCormack DNA-500:

http://iar-80.com/page5.html