12x7 tubes

Trying to match the right tubes with my system that  consist of a music fidelity m6si and dynaudio special forty’s speakers.

Brent Jessee is a great source ,

Tubemonger is another one ,  I replaced 3 RCA black plate 5751's 

with " slovakian " 12ax7's ( ecc803s ) in my phono preamp , Love Them .

The gain of a 5751 is 70% of a 12ax7 but you don't hear 70% less ,

the difference is about 1.5 dbs or a notch on you volume control .

I always buy my tubes through Brent Jessee - the tubes he recommends have always been a good upgrade to my gear...  Just got one a few weeks ago, in fact.

Brent Jessee recommend Tungsram 12x7 and GE 12x7 1950 USA long plate for my tube dac.Just looking for opinion on the tubes.

  +1 for Brent Jesse, read the tone descriptions they’re spot on. Next is what tone change is best for your system. After trying about a dozen brands of NOS tubes, I’m a huge Telefunken fan. That being said the Tungsram is a less expensive way to get the Tekefunken sound, then EI would be the next closest to Telefunken. I personally prefer the higher end German tubes, followed by the NOS American tubes. I’m not a fan of Mullard driver tubes as I find they put a vail over the music. However many people absolutely love them. Also Andy at Vintage Tube Service is excellent and I’ve also purchased from the Tube Museum although they’re a little pricy but great quality. Bottom line is you have to try them to find out. I spent about $3K answering that question 5-10 years ago. Happy Hunting, Mike B.