I don't own 20.1's but have heard them many times. bi-amping or using 4 mono amps is the way to go if you really want them to perform. One of my friends used 4 bryston (I do not remember which model) mono's with the bryston crossover. My preference would be for levinson, pass, Krell or similar highend amps (since the load on the 20.1's drops down to below 4 ohms.) They are great when you have enough power. Of course your needs will depend on the room etc.
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While not a Maggie owner I have owned Soundlabs forever and they are also a challange to drive. To date the best amps I've found are the BAT 600SE mono's. Total control over the Soundlab. Others that were good were Spectron, Theta's and Wolcotts but nothing even came close to the BAT mono's. Good luck!
Thanks keep those cards and letters coming I am printing all this out. OK what if Roger Sanders dies in 6 months who will service the Amps. I like Roger and he is why I ended up with Maggies. But!!! McIntosh has been there forever I realize I will change my mind over the next several years if I live (I'm 70) SO. I have met someone who is a local semi-genous. He a McIntosh fanatic however I can not realy test his 402's till I get my fuse put back.I will keep everyone informed. AS this plays out.
02-27-09: SwampwalkerI'll take that to mean the roof meets the walls at 12', but the roof peaks at 20'.My room is huge 30x40 with 12 ft walls and 20ft ceilings
The listening room has the internal volume of a 2,000 sq. ft. house with standard 8' ceilings. No wonder it's difficult (impossible?) driving the speakers to fill the listening area.
I heard a pair of 20.1s about a month ago that sounded great. They were using the Ayre 300w monoblocks. They were also augmented by a JL 212 powered subwoofer. And the demo room was nowhere near 30x40.
If you do the math, it's easier to see what you're up against. The 20.1s have a sensitivity of 85 dB at 2.83V, or about 1 watt measured at 1M away. 256 watts would produce 109 dB at 1M, but that's far closer than you would be sitting. Normally you lose 6dB every time you double the distance, but the 20.1 is a line source, so the distance losses should be cut in half and a second speaker (at least with a mono signal) adds 3dB to the volume. Still, 256 watts into the two speakers is only giving you 103 dB at 24 ft; 512w would give you 106 dB. Then there's the matter of the low impedance and the strain that puts on most amps.
Contrast that with the AV123 Focus Line Source LS9: It puts out 90 dB with 1w input at 1M. Being a line source, it only loses 3 dB for every doubling. So a 256 watt amp produces 118 dB at 1M, 115dB at 6ft, 112 dB at 12 ft, 109 dB at 24 feet. WIth two speakers that's 112 dB. It could theoretically hit peaks of 115 dB with a 500 wpc amp. With a 21-driver array and 12 flared ports, it can handle 500 watts easily.
I can understand you wanting to stick with your Maggies, but your listening room size calls for more loudspeakers, more sensitive speakers, or both. At the very least a good powered subwoofer would go a long way toward making it possible for the 20.1s to fill that enormous room.
I have MG 20's, and for the longest time was using a pair of Krell 300 MDA monos. Before that I blew up several HT recievers trying to feed these current hungry beasts.
I've used a pair of Fisher 80AZ monoblocks, and am currently using a pair of Dynaco Mk III's.
All of the above get hot to the touch, but I've had no failures running them 8-10 hours at a time.