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

Thanks, jbhiller.  I found the listings based on your earlier post that the (eBay) seller was in Ohio.  He does seem to stock a lot of interesting, reasonably priced tubes and has excellent feedback.

I may take the plunge and buy the 7581A's, and I may also pick up some 12au7's and 12ax7's for spares.

Thanks again

I tried them last night. Impressions:
Out of the box a little dry but extended in the treble. Very good bass. Clean and powerful sounding making my 1960s 6L6 Ratheon black plates sound a little tired. They did lack the sweet midband of the older tubes but they only have a few hours on them. Overall pretty impressed.

Thanks for the prelim review, noromance.  Please post a follow-up after you've lived with the tubes for a while.

I'm shy of 2 weeks into these tubes.  I have a good time running them in and with the holiday I was able to really let them run.  I'd say they have 40 hours on them now.  

To be honest, I think they changed a little but not too much from out of the box.  They "feel" like they settled in--yet that could be me getting used to them.  

I think these are more intimate in their presentation than the GL KT88, but not as bombastic or powerful.  They are not as shiny on top as the KT88 or as liquid as the EL34 in the midrange.  So what's to like? Much. 

These have an honest tweedy warm sound.  While the EL34 is--to my ears--sugary and heavy in a good chunk of the spectrum, this one is not but more so than the GL KT88.  What is odd and pleasing is that this one sounds better than the KT88 with percussion.  Snare drums really vibrate with the skin against the spring/rod or whatever they are made of.  Cymbal and strikes to percussion pieces of kit stand out--just a bit.  I liked that. 

The tube is not forward sounding to my ears.  There's a good chunk of energy pushing detail through.  

I'm going to get used to them more and then start rolling preamp/driver tubes through them to see what stands out, despite the swaps.  That should help me isolate their core characteristics. 

This is a fine tube and I am very pleased with it.  I'm still trying to figure out its fingerprint.  

A week or so later. Bass has got really good. Razor sharp. Depth and air have opened up. Highs fine. Midband fine if lacking a little sweetness (color; coloration?) Overall, very neutral, fast and clean. I will swap back my old reference 6L6 black plates to compare and report back.