Tubes and less sensitive speakers

@atmasphere  -  I stand corrected.  I've always based my efficieny for Maggies on their published specs, but the reasoning about the line source behavior makes sense.  I even took a moment to test the

...they sound just as loud ten feet away as they do when you are only a foot away.

and I agree.  In my ~20 years of Maggies in my secondary system, it was something that I never paid attention to.

Just goes to show, we can always learn something new every day.

One thing to consider is installing a high pass filter on the input jacks of the power amp (inside the amp)---or in a little box containing the filter plugged into the input jacks (as the video below will explain)---feeding the Maggies, to remove low bass frequencies from entering the amp and therefore the Maggies. The "corner" frequency of the filter is determined by the value of the capacitor used and the input impedance of the amp. There are formulas available on the internet for determining the cap value required for different amplifier input frequencies and the desired x/o frequency. Removing the low bass from the input signal to the amp will significantly decrease the power required to run the Maggies, and improve the sound of the amp and speakers as well (decreased power amp distortion produced, less excursion of the Maggie Mylar diaphragms). Removing the bottom octave (20-40 Hz) cuts the amplifier power required in half!

One amp to consider is the no-longer-in production Music Reference RM-200 MK.2 (review by Michael Fremer and John Atkinson available for reading on the Stereophile website), available used for around $2500 (one just sold at that price yesterday on USAM). The RM-200 was designed specifically to work well with low impedance loudspeakers, and puts out 125 watts into 4 and 8 ohm loads (the amp also includes 2 ohm and 1 ohm taps!). It uses only a single pair of KT88 (or 6550) tubes to produce those 125 watts, yet the tubes last around 10,000 hours.

Then add a pair of subwoofers to reproduce the low bass. Planar devotees have employed this tactic for decades, all the way back to the QUAD ESL of the 1950’s. I’ll post below a video Danny Richie of GR Research made on the subject of high pass filtering loudspeakers and adding subs:

https://youtu.be/65eFr2rKy3M?si=rftln4L2ryHM_yvf

Have you ever thought about getting a hybrid amplifier?  I’m currently using PS Audio BHk preamp and 300 mono blocks.  They have a tube input section and the amps have a Mosfet output section. Plenty of power and warmth.

The sanders magtec was developed for this type of speaker.they work well great synergy.the music room has one for sale around 4k.you can go to sanders sound website and read his white paper.enjoy the search

An inexpensive option would be a pair of PrimaLuna Evo 400 power amps in mono?  Each is capable of running with 8 KT150 tubes in Triode or Ultra Linear mode.  Just a thought.  Cheers.