Looks like Pass Labs' most powerful pure class A amp is the XA200.5 monoblock. Rated 200W into 8 ohms, and apparently 400W into 4 ohms. Shipping weight is only 180 pounds for each amplifer, and power consumption is only 700W each, presumably even at idle! :)
All of these numbers pale, of course, in comparison with the Atma-Sphere MA-3 that was mentioned. And I'm sure the prices of both are in the "if you have to ask" category, so I'm not asking!
Gryphon antileon signature will put around 500 watts of class A power into a 2.8ohm load. Pass xa 200.5 will put 400 class A into 4 ohm or lower loads and the 160.5 320 watts class A into 4 ohm or lower loads. Heavy, hot and expensive all. Only you can decide if it's worth it. My 4 ohm speakers (88db) drop to 2.5 ohms minimum and they will play at ear crushing levels with the Gryphon.
If the load varies widely by frequency around a 2.8 ohm average spec, then I'm thinking any tube amp, even the Atmasphere, may not be ideal.
I'm thinking one of the other Class A SS recommendations, assuming they double output from 8 into 4 and 2 ohms, or the Rowland or Bel Canto Class Ds that do same would be better.
Rleff comes closest to what you want with his recommendation of the Atma-Sphere. Keep in mind that Rleff discribes only one channel. Check it out on atma-sphere.com, it's really a product to behold!
For Thiel, think Pass, BAT, Mcintosh, etc. Solid state that has some emotion and will not overdrive the tweeters. Agree with the need for power, especially if the space is large.
Pass x600.5 does 600 into 8, and 900 into 4. Something like the first 80 is class A (for delicate passages), and then it switches to AB (for loud passages to keep it clear and delineated).
Here is a amp that can do it and heat the room up as well: Atmasphere's MA3;specs are: 500 watts/channel, 2-16 ohms Bandwidth 1-100KHz within .5 db IM distortion: 0.04% at full power Input impedance 100K single-ended, 200K balanced, selectable to 600 ohms Output section risetime 600V/microsecond 1/4 Farad of power storage capacity per channel- the most of any production amplifier!. The power supply chassis is 21" wide, 34" long and 12.5" high. Weight: 152 lbs. The amplifier chassis is 21" wide, 31.5" long and 15" high. Weight: 80 lbs. What do you think??? Got a american express black card??
Ledinhhien, if you were open to Mapman's suggestion of looking at 'greener pastures'. . . you may want to have a look at a couple of class D amps that sound particularly refined to me. In general, ICE power amps yield high output currents and high damping factors that make them particularly suited for difficult loads. But, to the contrary of class A amps, they are extremely efficient and runn rather cool to the touch. Traditionally they tended to sound a little "matter of fact" or even etched, but designs have been evolving rapidly, and some recent models are incredibly musical instead. My current prefs:
Jeff Rowland 312 stereo -- Substantially priced at $16K. . . but Audio Revelation on Agon seems to be offering a unit for $9.5K. It is also a relatively hefty brick at 70Lbs. I use it to drive a pair of Vienna Mahlers. . . which have somewhat wild impedance curves. I have written a sidebar article on this amp on TAS 188. . . I believe it's on page 80, part of my Vienna Mahler review. I just love this device!
Bel Canto Design Ref 1000 Mk.2 monoblocks -- heard the smaller Ref 500 at RMAF driving TAD minimonitors. . . and they were magnificent. I expect that the Ref 1000 will give you more heft and as far as I know even greater refinement than the smaller Ref 500s. Cost $6K. . . they look unprepossessing at only 15Lbs each, but do not let that fool you for a second! G.
The Parasounds have a hard time with loads under 4 ohms. I would think used Krell FPB. Lots of options with lots of power and run in class A the whole way.
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