Really...My favorite power tube is reissue that's not widely popular


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.  
128x128jbhiller
followup to my earlier post. I've had the 7581a in my PL Dialogue Premium integrated well over 100 hours. I didn't listen to the tubes out of the box and let them run 10 hours or so after installation. I didn't really detect any "break in" sound changes. The tubes are dead silent and I like the blue glow too. So compared to the original EL34's that came with the amp, no contest to me. Much more detail, especially bottom end definition and extension with a more dynamic and "faster" sound. Compared to the Gold Lion KT77, the detail and dynamics were about the same but the bottom end somewhat more developed and pronounced but still balanced. All three tubes I've used are very good, just a matter of your taste. I like a strong dose of tone without being over the top, that's the 7581a to me.
In addition to the overall tone and detail I’m very impressed with the bass definition as well. Tempted to order another quad - just because 
@noromance 
The stock Eico amplifiers are based on the Mullard 5-20 design.  It is a tried and true performer.  

The Jim Nichols circuit referred to above is a different design that uses a floating paraphase inverter instead of the Mullard long tailed pair inverter.  They are both capable of great sound.  So much depends on the execution.
Working around the Eico sidebar....good question re midrange. Let’s face it we are all looking for the “Goldilocks” tube, the mid warmth and tone of the EL34 and the highs and lows of the KTs. Have the 7581a’s now, trying to find time to plug them in.