If you run 6l6/EL34 variants, I HIGHLY recommend trying this tube out. The Tung Sol 7581A reissue. I've had these for a good bit of time and compared them against KT150s, EL34s (several brands), KT88s, and maybe another that I'm forgetting. They are a mere $30 a pop and they are the best tube I have heard. I know that's a brave bold statement to make as there is so much competition out there and the tube is very much under the radar from what I can tell.
After having these around for a long time (and in and out of the amp), I had them in and was nearly spellbound one night by how great they sounded upon reentry into my amp. I did a search and could only find one review, which I agree wholeheartedly with. You can find it here:
https://wallofsound.ca/audioreviews/amplification/6l6-vacuum-tube-review-tubes-courtesy-of-www-thetu...I am nearly incredulous there isn't hype out there about this tube. Simply my favorite tube. I thought I'd pass this along as it may be much cheaper to give them a whirl then fuss with a much more expensive power cord, cable, or other tweak.