I own a pair of the 0/96s and have tried a number of tube amps with them. My favorite pairing is a custom built pair of 300b mono amps, outputting 8wpc, and built by Bottlehead tech/designer. It uses Magnaquest nickel transformers and some hefty and expensive Mundorf silver gold foil oil caps. It edged out my Leben CS600x (which also sounds wonderful), and also a Shindo amp and a Woo WA5 300b integrated. Tried 5 other amps ranging from 2A3, 811, 845, and other higher power 300b variants, but these custom amps were the best (and happily like 1/2 the cost). I partnered with a 300b preamp that also uses nice transformers and vcaps. My room is 19’x18’ with 8ft ceiling.
I personally think 300bs are the best pairing for this speaker. I don’t want for more power, bass is wonderful and controlled and defined, and everything else sounds better than push pull amps I tried.
The EL34 amps add a tad more dynamics and the height of the listening window seems taller. But the 300bs add so much texture, detail, tone, and palpability. Honestly it’s super fun to switch around so I kept the Leben as a second unit, and pair it with Chartwell LS3/5a speakers.
I’ve owned Airtight amps, but not the 300b which I did listen to and quite loved - I had the ATM3 mono amps using EL34 tubes. Of all the amps mentioned, I would start with the ATM300. Airtight is a bit picky about preamps, and I never quite loved their own offerings. I would highly recommend looking into the custom builds like I commissioned, with the only caveat that the resale will be harder. That said, the cost savings over the more of name brands let me invest in some expensive cables and upgrade my digital, plus they sound better IMHO.
