Anyone have experience with the Tung Sol 7581a vs. EL34, KT66, KT88, 6L6

Another update...after being smitten (smote?) by Gold Lion KT77s and much preferring them to anything else in my little SE amp, I've switched to 7581As and now prefer them over the various power tubes I've stuck in this amp...including KT120s, 150s, KT88s from GL and Sovtek, and JJ (worse of the lot) and Gold Lion 77s. My tube drawer is gettin' kinda full.

My $,02 worth here. I have a pair of Quicksilver Mid Monos that allow for me to run almost any tube that is octal based. I have used JJ KT77, TungSol KT66, TungSol 7581A, JJ and EH 6CA7, and Gold Lion KT66. To me, and this is me and my gear, the TungSol KT66 is better all around than the GL KT66 as the TungSol sounds a little less "congested" as the GL tube can to me. But the big winner here is the TungSol 7581A. As much as I love my TungSol KT66 (huge soundstage, wonderfully full and warm mids, with deep bass and tantilizing highs without the hard sound) the 7581A does all of that time 10! This is an amazing tube! I have also tried the TungSol KT120 and I keep going back to the 7581A! The Mid Monos are supposed to be about 40wpc with the 6L6 tube and its variants. Well, you sure could fool me as I feel I have a lot more power than that and my speakers are not all that efficient (87db). If you can get away with the 7581A, I would do it. Viva Tubes has matched quads for about $90, a bargain. I like the 7581 a lot more than my NOS Sylvania 6L6GC, a whole lot more, and the TungSol is not nearly as hard to get.
Okay, so that was like $.50....Sorry...

The new RUSSIAN production power tube to beat in my system (LTA ZOTL40 AMP) is the Tung Sol 7581a (6L6 type). Less than $100 a quad, bettered the KT77 GL, El34 Mullard and Tung Sol 34b. The KT66 is a very linear, clear, smooth sounding tube. I felt the Mullards were a bit grainy on top, I do like the GL KT77, but the 7581a are more refined overall. The issue is the 7581a need at least 150hrs of burn in for them to open up. I still need more hours on the TS EL34b to proper evaluate them. The TS EL34b are definitely smoother on top compared to the Mullards so far. I bought the 7581a from Viva Tubes. Highly recommended.

I buy my 7581a tubes from Viva also, and only recently noticed the break-in phenomena...I haven't used any actual EL34s since my Had amp can run pretty much anything from 150s to 77s, and I have plenty of those, but yeah...I had recently bought another pair of 7581a tubes for my second Had amp, a Hot Rod version of the version I already own, and liked the sound of my original amp just a little more...until the tubes aged a little, resulting in a pretty much identical sound between the two amps...I'll likely sell one of these amps in the near future so keep your eye out for that in the A'gon tube amp sales area if anyone wants one of these things.

Zkidd, thanks for posting.... I have a pair of Mid Monos and love them, they are awesome amps. I have had several tubes and my favorites have been KT66 and KT88 Gold Lion but I have not really had long life with them.... I had a pair of KT66 that one shorted , big fire in the bottle and it took out my midrange on my speaker..... honestly would rather that happen than amp damage..... easy fix on a Klipsch.

So in a pinch I bought a quad of Apex matched JJ EL34 locally and they actually sound quite good but I like everything I have been hearing about 7581a tubes and think I am going to order a quad.