Expensive Tube Amplifiers

I don't deal in high powered PP tube amps any more, but for SET and low power PP there are plenty of modern offerings that will likely be superior to most vintage pieces. This is the golden age of low power tube design in that we have so many wonderful modern variants of film and electrolytic caps, resistors, transformers, tubes and many other parts to choose from. The circuits used in these amps are tried and true so what's not to like. 

My present amps include 845, 300B SET and Bendix 6094 PP, likely soon adding 50 SET., pre's running 101D, Cunningham 71A tubes. And I can easily modify these to exact sound preference desired by easily changing out parts in these point to point wired circuits. I don't need or desire vintage equipment with all these modern choices. High prices in vintage market driven  by collectors for whom the equipment matters more than the sound.

You get what you pay for..

For great quality amps, their IRON alone cost thousands of dollars. And doing parts upgrade as the OP posted above, those caps and resistors can also add up for a few thousands too. 

What is a 6C21 triode? It must be very unusual in order to promise so much Watts from only one single output tube. The 211 and 845 and etc don't even get close in SE operation. And it can be direct driven by a single input tube (no coupling capacitor if you believe the verbiage).

@lewm, yes it is a crazy looking tube! My previous amps were the NAT Audio 802 Generator mono blocks. I recall they were rated about 130-135 watts per channel but they were a push pull configuration with two 802 tubes per mono block. They also had three smaller tubes on each chassis. The chassis design looks similar but the Magma M’s are larger, have much bigger transformers and are much heavier. The Generators weighed about 80-90 lbs. The Magma M’s weigh 135 lbs each mono block.

The sonics are noticeably improved from the Generators. Don’t get me wrong, the Generators sounded really great! The only reason I replaced them was because one of the mono blocks stopped working and my tech advised me to just move on instead of trying to repair them. He said it was possible but would take a lot of effort.

It was explained to me that there isn’t the usual distortion that push pull tube amps have because of the single output tube. Apparently with push pull there is distortion when one tube hands off to the other tube.

You’re talking about crossover distortion, which is vastly overrated as a problem.  I have nothing against SE amps, and the Magma is certainly an interesting, if extravagant, design.  If you want a world class amp, you could also look at David Berning’s push-pull 845 amplifiers, which I can say from personal experience are astounding.  And speaking of "world-class," you could hardly do better than a competently restored pair of Heathkit W2 amps, a Williamson knock-off with Peerless output transformers.  A smoother, sweeter, more musically satisfying pair of 20 wpc amplifiers would be hard to come by.