I own 4 L1290's with the PA1 amps. I've only listened to one pair at this point and didn,t initially recognized the improvement. I first spent several years listening and enjoying them without the optional PA1 amps powered by an Onkyo M-504 and thought it couldn't get much better and assumed this was the best this speaker can do. I was wrong. With the addition of the bi-amped PA1 the improvement are not an initial recognized improvement, but as you start to hear detail in music that you never noticed, when you intently listened to this same music you've listened to innumerable times, its became apparent I was enjoying things in the recording I never noticed before.The best way I can describe the detail is "silence", that is the lowered distortion levels enables a spacing of silence between the notes of an instrument that wasn't there before. The sound stage became much broader and deeper, to the point the sound took on a presence of space totally different than my listening room. Yes, I was transformed into a different environment, I've had a lot of experience in design of car audio systems and have always said the best systems are those that you can play loud (sweet level) and still have a conversation with the passenger next to you and not raise your voice in an attempt to overide the music. In other words when everything is clean and you are not amplifying distortion along with the music its listening bliss and goose bumps and this is where I am now, in listening bliss. I'm pulling out all the old stuff and discovering anew those details that were always there, but not audible.
