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


I broke down and added another power tube (Tung Sol 7581a) to my collection.  That can get expensive as my Primaluna Dialogue HP Premium integrated has 8 power tubes.   

Why has this tube escaped me thus far?  Why is it not more popular?   Many folks don't sell this reissue tube.  

I think this is a great deal.  I was torn between the lush, thick midrange of the EL34 and the more evenly spread out sound of the KT88.  But the KT88, for all its more correct behavior didn't romance me like an EL34.  

The 7581a from Tung Sol can be had cheap and I really like them.  [I'll spare you all the audiophile terms].  They check the boxes that I was looking for. 

Does anyone have experience, information or knowledge about this splendid tube?  

PS  The next experiment is KT150s but I can't see doing it if I'm gonna lose any of that great EL34 midrange. 
128x128jbhiller
What can go wrong is Tube Reversal Compulsion Syndrome (TRCS) where an audio geek can't decide which tubes to use resulting in socket failure and, sadly, tube abuse.
JB, I have been flipping back and forth between the GL KT77's and the TS 7581A's for just under a year and I still can't decide which I like better. I have the same amp as you do driving my Goldenear Triton One's and both do an incredible job. I probably prefer the 7581's a little better as the GL's can sound a bit thin in certain frequency ranges, probably the upper midrange. I keep both around as I consider them both my "go to" power tubes. I find that using a softer input tube with the GL's help quite a bit whereas the TS's can sound great with most any input tube. I'm really not a fan of JJ tubes for hifi, I'm using a pair of their ECC802S long plates for input tubes and they sound fantastic. Cheap to try out too. I've been through so so many tubes to get to this point, I shouldn't even make this post as somebody will make a recommendation to me to try something new, lol. Take care.
@slmccaul , I hear you!  I'm in the same boat.  Both of these are excellent power tubes, and are reasonably priced. Do you have the ability to try KT150s?  
JB, I have tried the KT150's in my previous PrimaLuna ProLogue Premium integrated and they were my favorite non-EL34 type tube. I have tried a few of the KT88 types and all of them left me wanting that warm EL34 midrange. I classify the KT77 in the EL34 category and feel the 7581A's sound more like the EL34 class than anything else. My favorite EL34 was actually a Siemens RFT from the 1970-1980's. Very nice tubes but ultimately sold them after discovering the KT77's and 7581A's. These tubes have enough of the magic EL34 midrange plus do so much more than a stock EL34 that I feel both are the ideal tube for my application. As I always say, YMMV. To each their own.
After a long break from the 7581a tubes, I swapped them back in.  I was using Gold Lion KT77 reissues--great tube. 

The 7581a adds a bit of the power that the KT150 has and it seemingly has more headroom.  But, I say that without checking the specs.  That's how they sound.  

I remember now why I love these tubes.