Can single ended 211 or 212 amplifiers drive magnepan 20.7?

interesting though that a 18w 845 amplifier cant drive it but a 25 watt pass labs can! both are class A

@thegreenman The output impedance of the Pass Labs amp is much lower so 4 Ohms does not bother it. SETs on the other hand have a high output impedance and driving 4 Ohms make less power and likely roll off the bass a bit due to inefficiencies in the output transformer. 

If you really want to hear most SETs strut their stuff you'll need a speaker that is over 100dB 1 Watt/1 meter. 

guess between soundstage scale and beautiful sweet highs/mids w tube magic i need to give up one of them!

There are class D amps available now that make this statement false. I've been playing tube amps for over 50 years- I get the allure. Its hard to imagine that solid state could bring that, but its also hard to imagine that in over 50 years that technology hasn't improved. It has, right along with gas mileage and reliability in cars, cell phones and so on. IOW it had to happen sooner or later.  

@assetmgrsc: To achieve more than "pretty good" sound with a sub augmenting your Maggies, look into the OB/Dipole Woofer offered by Rythmik Audio in conjunction with GR Research. Magnepan has been working on a dipole woofer to mate with their speakers for a few years now (Wendell Diller has always insisted that omnipole subs---dynamic woofers in an enclosure---"do not work" with dipole loudspeakers), but no need to wait.

As for a tube amp to use with Maggies, Roger Modjeski designed his Music Reference RM-200 tube amp specifically for low impedance loads. 100 + wpc from a pair of KT-88 tubes per channel, 5,000 to 10,000 hours lifespan. The amp resided in the Stereophile Recommended Components List for a decade, Michael Fremer’s "reasonably priced tube amp reference." Out-of-production (though that may be changing), but available used for from $2,000 (original iteration) to around $3,000 (Mk.2).

Probably not saying anything new here but I’ve got parallel Set 45 monoblocks 4.5 wpc that are paired with large efficient horns that sound fantastic. I also have LRS+ that I bought as a holdover while the horns were being built. I would have to agree that they play music but not at anything I would recommend as a long term solution.

For Magnepan, Class D Audio GaN amp for about $1k and done!  
 

Made in the USA as well to boot. 

@atmasphere thanks for the detailed and thorough explaination as always! 👍👍☺️☺️ will go check out class D amplifiers, esp those ganfet ones :)