[BeatleFred]

I'm a vintage Sansui enthusiast (www.sansui.us) and in my main system I was vertically biamping two AU-X1 amps I have to my Infinity Renaissance 90 speakers. Preamp is Sansui CA-2000. This preamp has TWO pairs of Outputs, so connecting to two amps is very easy to do- no splitter required. The AU-X1 is an integrated amp with separable pre/power sections, so I simply switch over the AU-X1's to Power amp mode.

I had a problem with one of my AU-X1's the other night so in the meantime I rearranged my setup and now have a horizontal biamp arrangement- using my Sansui AU-20000 (170W) and Sansui AU-919 (110W). I chose horizontal for this because of the two different model amps (as opposed to vertical and identical AU-X1's).

I noticed that I am getting tremendous bass response with the higher wattage Au-20K driving the Infinity speaker woofers and the AU-919 driving the Infinity Emit tweeter/midrange. Out of curiosity, I swapped the amps so that the lower wattage AU-919, now drives the woofers, and the AU-20K the high/mid- and the sound was diferent- less bass, more brightness.

So, my question is: Does this result cause a dispute to the belief (by some people) that most amps sound the same? Does biamping really reveal that two amps can produce different sounding results? Is the 170W AU-20000 and the 110W AU-919 too much difference in wattage such that the bass becomes more prominent than the treble/midrange?
 
 
 
Sincerely, B/F.

[nathanm]

I did this same test recently, with swapping around which amp was driving the woofer or tweeter.  It sounded different (worse) swapped, but I attribute this to overall gain difference in the amps, so the frequency response "inverted" basically.  If both differing amps have identical gain characteristics then you could evaluate the sound based on other factors, but what I noticed was that one type of amp had more volume than the other kind.