Phono preamp tube rolling.

@tomwh The ares manual suggest that switch between 12au7, 12ax7 and 12at7 in case to play with the gain…. I did it successfully with no any problem.
My priority is listening to music and I’m not really interested in deep technical details of the tubes, it’s required lot of time. maybe I’ll explore this when I’ll retire… for now I just want to listen and roll, listen and roll :)…to figure out what I like the best…when I’ll be interested in tech questions I’ll post that… my current post is about something else as you could see. 

Andy at Vintage Tube Service in Michigan.

i was hoping @mulveling would weigh in also, he has a wealth of experience and some great phono stages as well. Where did you end up w the Herron ? 

on ARC , i got some serious hours out of the 6H30 in my REF5se, but keep changing the oil !

Fortunately, these small signal triodes tolerate a lot of abuse and can still sound”good” while being abused, if you don’t measure anything and are subject to listener bias. Which is all good. But it’s best not to draw conclusions like A is better than B based on a blind substitution of one for another type. If you think it’s fun and rewarding to tube roll, I submit its even more fun if you do some reading to gain a better understanding of what you’re doing. The science is fascinating.

@chakster 
thank you for a lot of useful info.
You right that Japanese tubes are not discovered well. It wold be interested to hear from people who tried them.  

I tried the National brand 12AT7, and I did not like them compared to at least four or five other brands of European or US origin. In fact a Chinese made tube was the best of the bunch in my 12AT7 survey, but it had a very short lifespan which I considered unacceptable. The next best were GE gold star and Mullard. ECC81 is the Euro equivalent. ECC81= 12AT7.