@Golum
Man, I've been avoiding posting because I've had a lot to digest and don't want to come off as a hysterical teenager with each tube that catches my fancy.
The Brimar, it'ss a killer tube. So far, I consider the Brimar on par with the U50 in my system. It's warmer and more engaging, still has great see throughness. It's definitely more refined than the U50 as well. Refined in the sense that it does delicacy and nuance better. For the price, it's the best buy of all tubes.
Please take my view with a grain of salt because, neither tube may be completely broken in, and before I could do so and completely compare both, the Raytheon RK60 adapter came and opened a new can of worms. Based on limited burn in for all three tubes, this is my favorite of the three. It sort of marries the virtues of both the U50 and the Brimar. It's like a warmer U50, but more laid back to allow for inflections and flutter. Soundstage is cavernous compared to both, and bass is tight and deep. Voices also sounded more real with the RK60 out it the three. It cost me slightly more than the Brimar + adapter. A great all rounder. Like a warmer 596 without the constricted images and soundstage. All this, IMHO.
This entire exercise did prove futile though. I was hell bent on finding a giant killer, cost efficient tube, that did everything, but once the U52 showed up, I couldn't take it out of the DAC, after tuning everything else to counter it's extreme warmth. And then, the 422a appeared and it was curtains for the U52.
Amazingly, not to upset anyone, but I consider all these rectifiers, RK5U4G, 596, U50, Brimar, RK60, U52, and 422 as better than the Tak rectifier IN MY SYSTEM. The gentleman I sold the Tak to loves it to death, which makes me extremely happy. I believe it would have done wonders in an amplifier.
Sadly, I couldn't find my giant killer. What the U52 and 422a bring to the table is in one word transparency. The feeling of really listening to musical instruments that are well formed. Complete control in moulding the signal into images that at least pretend to breathe. Images are humongous compared to all the others except for the Tak. They're also both significantly warmer yet surprisingly more revealing - something my Mundorf caps can appreciate. The 422a's transparency and soundstage surpass that of the U52.
I'm waiting to receive
@Golum verdict between the Elrog and Acme 274Bs, after which I'd like to compare one of those to the 422a. If I'm not batshit crazy by that point, a WE274B may be the final test after selling off some of the participants.