McIntosh & Maggies - am I hooked-up the best way?

I recently upgraded my two channel system - after researching Audiogon and serious negotiations with my wife... Here's what I've got;

* 2 McIntosh MC150 amps set up as mono bridged (note I had one originally)
* McIntosh C712 pre amp (also part of my original system)
* Denon 3910 SACD player (with Underwood level 2 mods)
* Magnepan MG 3.6 speakers (with Mye Sound stands)
* MIT bi-wire speaker cables
* Monster power and interconnect cables through-out
* 2 Monster Power HTS5000 power centers (also have my HDTV, satellite HD reciever. D/A converter (now only used for the satellite audio), VCR and cassette deck in the mix, so I needed more plugs!)
* Audiopoints brass points under amps, preamp and speaker stands

The sound is awesome... (a;though my wife claims to not be able to tell the difference...) My question, "are my amps and speakers hooked-up the best way?", is because when I have the volume up, then crank up the bass and loudness on my pre amp, the amp power meter lights pulsate with the music. While this is not a bad looking effect - it concerns me that the power meter lamps are influenced at all. I know that Maggies will take all the power (current) they can - but that is why I'm using the MIT bi-wire speaker cable... any thoughts, comments or suggestions would be appreciated!
You may want to try them in 2 channel rather than bridged,
and biwire vertically or horizontally.
It may be an easier load on the amps if they don't have autoformers.
I'm not a big fan of using bridged amps, and since you have a pair there is no need.

Also, leave the bass and loudness control alone, get a sub if you want more bass.

I think you are light on power, I ran 400 watts x2 into
MG12's when I had maggies.
Try one MC150 for both Maggies, lowish volume and compare to the bridged sound. When I tried bridged Mac, it seemed a little more tight as opposed to relaxed. I prefer relaxed. Next try passive bi-amp. You'll like it one way more than another. We're all free to gamble. My bet would be on the passive bi-amp. Good luck.
Thanks for the suggestions... I'm assuming I have decent power here - the MC150s are rated at 150W per channel into 8 ohms, so in mono bridged mode they are 300W into 8 ohms, and since the Maggies are 4 ohm loads, they should each be seeing well over 300W.

If I understand the suggestions, I should try bi-amping by running two sets of non bi-wire speaker cables, one set from each amp (unbriged) to each speaker. I may have to wait for Christmas for Santa to bring me new MIT speaker cables...
Mike, get yourself some cheap 12ga wire, Home Depot or Radio Shack, short lengths of course. Hook your Macs up in the different configurations. If it's real noticable one way over another you'll know what direction to go wire wise. Do you already have a Y-splitter from your Pre to get 2 lefts and 2 rights to your amps or can your Pre drive 2 sets of amps already?
You bring up a good question... while my pre-amp does have two sets of outputs - I'm not sure about using them at the same time - I'm using the set of balanced (XLR) outputs now (one to each amp)... the other set is unbalanced (RCA)... and, I do have a pretty good run (2M) to my right amp (the pre-amp sits just below the left amp).

Maybe I'm just as well leaving things as they are and enjoying it! The sound is truley awesome. My only reason for posting in the first place was my concern about the amp power meters pulsating at high volume, loundness, and bass... I'll just keep the dBs in check (my wife appreciates that anyway).

Thanks again for your suggestions and comments.
Were you able to do a before and after comparision regarding the Denon? I have a 3910 and I was considering the Underwood ultimate mod/
Use Cheap Depot wire to run the Low freq. section, 12 gauge copper will be the same sound as just about anything honestly for the low end in this case...

Put both your amps back in stereo mode, one will be used for your left channel, and one for the right channel.. Now you have 4 Channels of amplification, use either of the channels to hook up your bottom end and the other for your mids and hi's, I am assuming you have bi-wire on the speakers, 4 binding posts total on each...

Now Run the Balanced Cables you have to the channel's being used for the Hi and mids, and the Bottom end with a cheap RCA cable from your left over RCA outs on your pre... This will have very little effect on your bass with the cheap speaker and rca cables, and not running balanced on those 2 less criticle channels to the bass is fine, trust me I have tried it and very difficult to justify all the extra money for better cables to run basically dedicated sub frequency volumes to your woofers or low freq electro panels.

Your amps will probably open up a little more running in the stereo config and sound a bit better balanced now that you have low end dedicated channels. This is verticle bi-amping, and believe it or not you might find less need for much tone control adjustment this way, but in mono you are making the amps work a little harder and basically not as clean in this scenario this is my opinion over just running the 4 dedicated channels...but you gotta try and it is relativley cheap to experiment and find out the better amp configuration...

And remember your crossovers create a lot more loss of power, at least the hi's and lows are feed seperate this way and have a better seperation on the frequencys that suck down the juice.

I have done similar testing with Mono vs. Verticle biamping, and found the biamping a bit better with the same amp, mainly cause I think that you are able to Tax the power supply when needed for more bass on one of the two channels vs. 1 single channel the whole time saturating the power supply continuosly.. I could be wrong, but seems somewhat logical depending on how bad the speaker soaks it up fast, plus this will up the efficiency on the channel running the hi's and mid's with cleaner seperated power and not being taxed by the bass simply takes less watts to feed.. so you could essentially get higher DB at lower volume knob for the top end frequencys. Gotta experiance it yourself to find out however, and not to mention I think I have noticed that the Heat(temp) of the amp will reduce if not running in Mono vs. stereo, but I do not have the amps you do, but have heard and owned Mcintosh and like the stereo style unless they are Monos period built that way, but I would not bridge mcintosh without at least trying the verticle biamp first.
Matrix- thanks for the great suggestion! I had to wait until after Christmas to try the vertical bi-amping (Santa brought an HD DVR that needed the entertaiment center pulled out to install, so I could then experiment with the amp wiring). It was worth the effort - big time. The sound is more open - seems more natural... like the amps aren't working as hard. Thanks again for the suggestion - I now know that I am hooked-up the best way!