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

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. 

Anyone try the new Tung Sol EL34B?