Luxman Class A Integrated Slight Buzzing Noise

It's the design of the Luxman Transformer. I have a 1968 Richard Allen (Sugden) A41 Pure Class A amplifier, the worlds first Pure Class A production power amplifier, which utilises an EL transfomer. It doesn't buzz, so why does the DC offset on my mains not affect this 47y.o. amp? For one the transformer's physical size/weight, at least, in comparison to it's 10 watt output is overkill, the Luxman on the other hand has a disproportionate sized EL transfomer, regardless of material quality or design technique, I suspect, in relation to the 580VA or so that Luxman's 590 amp demands of it, hence possibly a higher propensity for Magnetostriction occurrence. The Luxman integrated Class A (note: not Pure Class A) amplifiers sound pretty amazing, but the modular/plug+play build makes me wonder where the tangible value these amplifiers are. I'll add as a final point, why do Moon (a relatively young amplifier firm), Sugden (around 35 years after Luxman began), Audion (a valve amp manufacturer that use both EL and Toroidal transfomer's in their designs) and Krell amplifiers not buzz the way my Luxman does? I believe the answer can be found in my earlier post concerning Magnetostriction, which can be controlled for the most part by transfomer design.

Deedo--I have found your posts very interesting and illuminating. Transformer hum and buzz has, off and on, bothered me for years. All the way back to when I owned an Adcom 535 (long time ago). I had a big Nackamichi for about a day (re-badged Threshold), that also hummed. And a big Sony from the old ES line that didn't. I had concluded that it was crap on the line coming into the house, combined with the design of the transformer--i.e. that toroidals were a lot more prone to it than other shapes/designs (the Sony had EIs). I've steered away from toroidals for a long time, first with a Cary and now with an Ayre. (I discarded Plinius as an option because there was a lot of anecdotal evidence on line about humming.) The idea that it all depends on the size/weight, the materials, and the exact construction, rather than the basic shape/configuration, is something of a revelation.

I have about 200 hours on my L590ax. There is no hum whatsoever. I'm using an Isotek Acquarius for power conditioning.

Excellent detective work. My C-J tube amp has a bit of a hum when no music is playing. Some call it tube rush. I don't worry about it because it does not interfere or create issues when I play music. Does your hum become undetectable when you play music?

Bump-- my second hand Luxman 550ax has that slight hum/buzz from inside the unit case. You can def hear something 8ft away. Its not bad but if you lock on to it--will bother you!! Any solutions since 2015??