Hi Rock,
Yes, regarding test #3 you did, I'd agree that the NAD is entirely capable of handling the incoming signal with its own preamp/amp, and better with fewer complications than using your outboard preamp.
I'd agree with John K's recommendation: an AV receiver with 100 watts per channel should be more than adequate to drive your M22's to high volume undistorted levels in your particular room. YOu can use the receiver's internal crossover adjustments to properly link your M22s to the EP500 subwoofer without having to drive the M22s "full range".
Quite a few posts back, you mentioned that you'd turned up the NAD "all the way" until it couldn't go any louder. Do NOT do that anymore with an amplifier or receiver -- you risk damaging the voice coils of the M22s tweeters/midrange drivers with a distorted "clipped" signal.
You may have already done some damage but it's hard to determine that without checking each driver in the M22s.
As Mojo suggested, leave the NAD's "soft clipping" feature on unless you hear increased distortion. To be honest, I've never seen proper tests of the Nad soft-clipping feature so I can't comment on its effectiveness.
And, like John K (and Mojo), I do most of my music listening with Dolby Pro Logic II (or the equivalent from dts). Harman/Kardon receivers also have a third music-surround mode called "Logic 7" (designed after Lexicon, which Harman owns). Logic 7 on my H/K receiver sometimes seems to add a little more image depth on good recordings than ProLogic II or dts, but the difference is slight.
Like Mojo says, if you don't like the surround effect with some recordings, just turn it off and listen in stereo. You do have to adjust the ProLogic II or dts surround settings to your own taste to get the best results.
Here is a link to an article I wrote for Axiom years ago on the fundamental flaws of stereo music listening:
http://www.axiomaudio.com/blog/stereoflaw/You can find it under "Blogs" on the Axiom website.
The enhancement in realism using 5.1 surround (or greater) for music listening with good recordings sometimes is dramatic. Other times, it's modest, but in many cases if you switch off the surround mode and go to 2-channel playback, the image collapses into a much less realistic, disappointing flat line between the speakers.
Regards,
Alan
