6.1/7.1 setup and Preamp Outputs

[stinems]

I'm looking at pulling the trigger on an H&K receiver and using it as a preamp/proc, feeding the preamp outputs to a separate multichannel amp. The main reason for this is that I want to be able to comfortably drive a 4 ohm load, which is lower than most mid-fi receiver's published capabilities. However, the multichannel amp I have is only 6ch. Rane MA 6s

It is my understanding that there are currently only 6.1 discrete formats on DVDs. Any 7.1 systems run on processor based DSP extrapolation of the 6.1 information from the DVD. I'd like to harness that 7 channel goodness if at all possible. Could someone clarify or confirm? Has anyone used a single rear center channel in a 6ch scheme instead of two rear surrounds getting fed the same signal?

Is it possible or a good idea to just use, for example, the pre-outs to the separate amp to drive the 4ohm mains and center (biamped maybe?), but use the receiver's amp to drive the four higher impedance surrounds? Or is it an all or nothing kind of deal with the pre-outs? Is it okay to mix and match amps in a system like this?

~Sam

[Karma]

HI stinems,
While I am experienced in stereo audio I'm relatively new to HT. I can only tell you what I have done. Is it good? I think so. Others may disagree.

I am doing exactly what you are describing for my 5.1 system. In the process of arriving at this point I have also implemented 6.1 and 7.1.

Currently, I have a Krell KAV-3250 three channel power amp driving my front three speakers which are B&W 805S's and the HTM4S center. The Krell gets it's signals from the processor preamp outputs. My surrounds are SCMS mounted on the rear wall which are driven by the built-in amps in my Denon 3805 receiver. Thus, I am currently using only two of the 7 built-in 3805 amps. I used four channels with the 7.1 set-up. I do think this arrangement gives a lot of flexibility for experimentation. Plus, if the Krell ever craps out, I am covered by using the Denon amps. I really like this arrangement.

When I had the 6.1 and 7.1 configurations the surrounds and rear channels were always driven by the Denon's amps. I think this scheme works well. I have never obviously run out of power on the surround channels. Of course, the size of the room will dictate power requirements. Mine is fairly small at 1400 cu. feet. The Krell is rated at 250W/channel and the Denon is 120W/channel.

I think matching the surround speakers to the fronts is more important than matching amps as long as all the amps meet the basic power requirements. The best thing I did was take Rebelman's advise to buy the SCMS surrounds and dump the original B&W 600i's. It made a huge difference. I learned that the surround speakers is not the place to cut corners.

Sparky