Dazzdax: Now we are getting somewhere. 4K is too low for most preamps and will result in the exact problem that you've described i.e. bloated bass response and trunctuated treble output.
My Dad ran into the same problem in his system several years ago. The dealer had set him up trying to drive a 5K Ohm amp with a preamp that had a higher output impedance. The sonics sounded bad, but much of that was also a speaker based problem. In effect, his whole system sounded bad, so you couldn't really point the finger at any one given thing. In this regards, you might be a lot luckier : )
The simplest solution here is to install series resistors either at the output of the preamp or inside each of the amps. While this will attenuate some of the signal fed into the amps, it should solve much of the tonal balance problems that you're experiencing.
The key here is to find a value that is low enough not to eat up too much signal while being high enough to remove the current drain from the preamp. If you were happy with the tonal balance of the system using one amp per speaker and simply wanted better but equivalent performance, installing 8 K resistors in series with the input of each amp or output of the preamp would put you back appr where you started at.
Personally, i would install the resistors in the amp as that keeps the signal level higher through the interconnects. This is beneficial in more ways than one. Secondly, i would probably use resistors in the 12K region, as this would bring the total load up to appr 10K or so when running both amps in parallel. Even if you chose to run one amp per speaker, the input impedance would be 20K, which is still quite reasonable and easier on the preamp. You should also keep in mind that different brands and types of resistors have different sonic attributes, so you may have to pick and choose your poison there too.
You might want to discuss this with the dealer / manufacturer at Acoustic Reality and see what they suggest. Hope this helps and solves your problems. Sean
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