300B Tube Amps with 15/16 Watts Per Channel?

Art Audio Diavolo Copper Ref SET. Verdantaudio.com

I think it maxes at 13wpc, but you must use the EML 300BXLS. You would need to discuss having the amp wired to the higher voltage psu transformer windings and bias circuit adjustment for that tube to get the higher wattage. The Western Electric 91a Boasts 20wpc with their 300b and special circuit and solid-stage rectification, (I prefer tube rectification for SET), but that 20wpc is at 10% distortion which is an order of magnitude more than necessary to get the 2nd/3rd harmonic distortion which provides the euphonic magic along with that floaty liquidity and palpable midrange and eerie micro-dynamics . I don't do parallel SET (anymore) after owning the ALLNIC (Quad-Parallel 300bxls monoblocks which will give you 60wpc, but only by using quad-pairs of eml 300bxls (KR AUDIO BXLS MAY ALSO WORK). $25k New or $10k-15k used and theg are made in  S.Korea). I don’t recommend parallel-set because it’s not as pure sounding lacking some magic (though better than pushpull or ultra-linear or the phony triode-mode by disabling 2 stages using a pentode) , very expensive, it’s a class A amp with massive heat output aka a space-heater, retubing is way more expensive especially for EML or KR 300bxls. I’ve done all of this before. Do you like running the ac in winter all the time? 

i now own a muzishare R100 805 model Don’t be confused the 300b is only a Driver-tube for the 805 triode) It produces a real 50wpc and for the money or 4x the money, I really love it. I run TOTL Psvane Acme 805 ($650-$850 ebay) and its the best bang for my buck ive ever had with a SET AMP. It Drives my Legacy Audio Whispers XDS dual-open-baffle speaker exquisitely . Specifically it drives each speaker’s 4x 7” mid-woofers, and the dual AMT custom midrange and tweeter. The open-baffle 15” bass drivers (humblebrag, all eight of them) are actively powered by 500wpc ICE Class D amplifiers. The speakers are 4ohm 94db.
Ive been doing SET Tube amplifiers for most of my 40 years in the hobby. If 50wpc is overkill, the R100 845 version ($2800-$3500) or the $5k-$6k Flagship X30 845 muzishare.will give you 25wpc. I like the PREMIUM PSVANE ACME 805 tube A LOT! I may buy the X30 845 next myself. (Skip the Line Magnetic or Willsenton) Best of luck.

Here is balanced 300B push pull amp Blackbird Monoblock

https://www.spatialaudiolab.com/blackbird-monoblock

Don't listen to @brianlucey 😝, I am struggling to remember if I bought his used pair of Allnic A6000 monoblocks. I could be wrong! This much I will admit: i neglected to mention the model in my previous post, I couldn't be happier with the transaction, great packaging and like new condition, he is correct regarding running two pairs vs quad 300bxls, they are meticulously crafted, and we're very impressive driving anything, but between the heat, retubng expense, and that they were IMHO almost too clean, aiming for superb dynamics trading something in tonal colors, and some delicacy with micro-dynamics. I believe the feedback design might be what caused this.

I sold my A-6000 for lower wattage single ended triodes - all you describe is regained.  Parallel circuits are difficult to engineer and that is the trade off.  But the A-6000 is far superior to push-pull - in my exceedingly subjective opinion. 

The other option is to look at 845 amps that use 300b(s) to drive the 845 tube.