Bi-Amping questions

What you are proposing is known as passive bi-amping. If your NAD pre does not have two sets of outputs, then you will need to utilize some form of "Y" splitter, or have interconnects built with a "Y" split. This will allow you to hook both power amps up to your pre-amp simultaneously. There are basically two different methods for passive bi-amping. One is Horizontal bi-amping the other is called Vertical bi-amping. Horizontal bi-amping is usually the preferred method. With Horizontal bi-amping one amplifier will power the high frequencies of both speakers while the other amp will power the woofers or bass section of the two loudspeakers. Vertical bi-amping is accomplished by having one amplifier driving the highs and lows of one speaker while the other amp drives the highs and lows of the other speaker, almost like mono-blocks but with the amp remaining in stereo mode, one channel of each amp will be hooked up to the highs and the other channel will be hooked up to the bass of each speaker. This is an effective way to add some headroom to your system. Some even feel that passive bi-amping has other sonic benefits, but my personal experience with it has yielded only higher output not better sound. That's okay higher output is the goal here,right? Try both methods and see which one you like best. If the Adcom amps are bridgeable this would be the course of action I would recommend as it will offer even more power than passive bi-amping, plus you will not need any "Y" adapters or cables.If your budget was ever to permit, I would highly recommend selling the Adcom power amp, purchasing a Linn power amp and later adding a second Linn power amp with some cards for active bi-amping. Active bi-amping, using electronic crossovers to re-direct the appropriate frequencies to the appropriate speakers and drivers, is a whole different kettle of fish from passive bi-amping and will provide a large increase in sound quality. Linn has been proponents of, and have offered active bi-amping options for most of their speakers for sometime now. I have heard Linn active set-ups compared directly to the identical passive set-up and there is no comparison. The active system wins on all counts. Much better defined and lower bass, wider and deeper soundstage, higher power handling and SPL, and the list goes on and on.

Adding the 2nd Adcom amp and bi-amping (horisontally or verically - you will experiment with that) is the cheapest solution.

You are probably much better off by selling your Adcom and as suggested above buying Linn power amplifier (or similar).

By-ampling is only good when your amps cannot deliver required current into low frequency area . In such a case your treble/middle range will be undistorted. Human ear is much more sensitive in that area and not in bass area.

Otherwise one amp (single ended or fully balanced) is better.

Regards,
Simon

I use two Pass ALEPH 30 for passive vertical biamp.
With this biamp. type you will have better channel separation and less distortion, but only increase the power in 3db.
If you need more power, go with a bigger power amplifier.
Remember that you have to add an extra Interconnect cable for biamp. and your speaker cable must be prepared for it.
Hope this help you.

You'll find this post by the noted designer Steve McCormack to be well worth reading.

Also, I believe that contrary to widespread belief the 3db power increase (i.e., twice the power) that is commonly cited for bi-amping vs. single amping will in many and probably most cases not be realized. In the common situation where power delivery of the single-amp arrangement is limited by voltage swing capability (i.e., by clipping, as opposed to being limited by the amp's output current capability), the power increase provided by bi-amping will be 0 or close to it.

For equal volume to be produced in the bi-amp'd configuration vs. the single-amp'd condition, the two bi-amp'd amps will both have to output the same voltage swing as a single amp would have to. So the volume level at which the clipping point will be reached will not be changed by bi-amping, other than to the extent that the available voltage swing capability of the particular amp design may vary as a function of current demand (although that may be significant in many cases).

What will be helped is that the amount of current each amp channel has to supply will be reduced, which may improve the sonic performance of the amp even if it would not enter current limited conditions in the single-amp configuration. Also, vertical biamping will provide the benefits Steve describes in the post I linked to, eliminating crosstalk across the common power supply and ground system that can occur to some degree with some amps in single-amp or horizontally bi-amped configurations, since in those configurations the two amp channels handle different signals.

Regards,
-- Al

With "passive" biamping each amp must swing the peak-to-peak voltage of the full range signal, so, as Almarg says, no significant power increase will be realized.

On the other hand, when you use an electronic crossover (real biamping) at a given total signal level, the peak-to-peak voltage swing of each amp is reduced. The high frequency signal does not ride on the Low, and vice versa.
Some increase in total power will be realized.

However, the greatest benefit of real biamping is the reduction of IM distortion. This was more important years ago when amps commonly exhibited more than 1 percent IM distortion.