Damping factor or watts?

There's a lot of myth about power, gain, and DF. There is no universal, all encompassing rule. The age old JBL reinforcement manual recommends an amp with 2x the rated power, in watts, of the speaker at like impedances for optimal driver control. Dare somebody with a pair of original Ohm Walsh's to try putting 2x the power into them!(If you're silly enough to try they still make replacement parts). Bottom line, read the specs only to make sure you're not doing anything dangerous, then trust your ears. It's far to easy and tempting or manufacturers to confuse, hide, or outright lie to end users on the spec sheet

Damping factor is is an amplifier's ability to control a woofer's motion after the drive signal has ceased. For example: if you drive a loudspeaker with a bass drum whack, the woofer's inertia and resonance in the enclosure will cause it to keep moving after the signal has died away. a This is a form of distortion that alters the music signal's dynamic envelope. The diaphragm of the Maggie is so light, and it's excursion so short(because of it's surface area) that the damping factor of your amp is virtually a moot point. The MMg's are only rated down to 50hz anyway(they're already rolling off at 80hz). Bottom line: Don't buy an amp to go with your Maggies based on damping factor. I'm using a Hafler TransNova 9505(255wpc) to drive my subs because of it's high damping factor(1000) and fast slew rate(150v/ms). Not an expensive amp at all(for high power and damping factor). BUT- I love tubes for my Maggie mains, and my Cary SLM-100s do a wonderful job. I've driven the Maggies full range with the Carys(and the Hafler for the heck of it) and they don't sound bad at all. Nothing beats the dyanamic range and transparency I get by bi-amping though. One more thing- Damping factor is related to the amplifier's output impedance. The lower the output inpedance, the higher the damping factor. The impedance of the cable between the speaker and amp decreases the effective damping factor of your amp. Keep you speaker cables short.

DF will not control the driver excursion. The driver will move somewhat with inertia when the signal stops regardless of DF. What happens is that the moving driver acts like a microphone as the cone moves in the voice coil creating an emf. If the amplifier DF is very high, it's low output impedance presents a short to the speaker. This prevents a back emf to the speaker which could cause the driver to oscillate as it repeats the process.

What stops the cone (or controls it) is the air mass loading on the driver from the speaker enclosure (Q). Also, the crossover and the voice coil add to the overall DF in addition to the speaker cables so the amplifier DF will change once hooked up to a speaker. And with a planar speaker, the air loading is quite high which helps things out with low DF amps.

Then there are the unavoidable compromises in amplifier design: for an amplifer to have a high DF it has to have a very low output impedance which then will require more global negative feedback. This creates another problem to deal with in terms of distortion. Bottom line is that numbers don't tell you much.

There are reasons (immaterial here) why some ribbon devices may sound slightly better with a medium DF than an extremely high one -- hence the use by some of tube amps.

Otherwise, your system looks fine on screen -- so the problem must be in the listening! What's bugging you?

While Back EMF is not completely irrelevant in this discussion, I didn't feel it warranted inclusion in the definition. For a better understanding of "damping factor", see these: (http://en.wikipedia.org/wiki/Damping_factor) Particularly pg 1, para 2,3 / pg 4, para 1 (http://www.classic-audio.com/marantz/mdampingfactor.html) Notice how often the word, "control" is used. Tube amps almost invariably have low damping factors. To say that Maggies need a high one, but that they sound best with tube amps is contradictory. Here's an interesting little article on the MMg's you may enjoy Hlgoh: (http://www.enjoythemusic.com/magazine/viewpoint/1199/donibbles.htm)