Using a Pre-Out to Bi-amp

The amps need to have the same gain. If they don't, the drivers with the lower gain amp will have a lower volume than the drivers driven by the amp with the higher gain. The effect would be like having a balance control between the drivers, as opposed to a balance control between speakers.

Given the speed of the signal, I would not expect any time delay in this circumstance to be audible or significant.

On a related point, this reminds me of a review of a Bryston amp that I read some years ago. The reviewer was on record on a number of occasions as saying that a good amp circuit should be designed without negative feedback. The reason was that you can't take a signal and then feed some of it back to eliminate distortion as you can't correct a signal that has already occurred! In other words, the inherent time dealy involved made the exercise futile. In the Letters section of the next issue of the magazine, Bryston responded to some of the points in the review. I think it was one of Bryston's chief designers, Mr. Russell, who regretted the reviewer's continued insistance on spreading blatant misinformation, or words to that effect.

Time delay in speaker drivers is important because you have drivers pumping out sound that travels "only" at the speed of sound. It's also important in the reconstruction of analog from digital signals, jitter, for instance. However, these time effects are occurring at the interface between electrical and mechanical energy or between digital to analog conversion respectively. Signals traveling around the speed of light for a few extra inches inside an amp are another matter.

Anyways, I'll let the engineers argue this one. I will however, tweak the nose of the naysayers by saying that I biamp with different amps and I have no problems at all. All I require is similar gain. I hope that doesn't bother you too much.