I am a hobbyist without much experience regarding different tubes so I can only say that I replaced the stock Chinese tube with this EH 12AX7 in my Gretsch G5222 and I immediately noticed a difference. Overall just clearer in both low end and high end and louder but I also replaced the Chinese 6V6 with the TAD 6V6 at the same time! So which tube improved the sound dramatically...well both! The stock speaker is still not great but both these tubes already make my amp sound 70 % better!

Have used several different pre-amp tubes, JJ, Tung-Sol, Mullard, Sovtek and in this price range I tend to always fall back on the EHX 12AX7. Never had an issue with noise or microphonics. I've dropped them and still never had a problem. They last and sound great, nice harmonics and crunch without being fizzy or dull. I haven't noticed a difference I can pin-point between the regular and gold pin tubes, but I suppose the gold pins are good if the rest of your amps connections are gold plated.

Swapped out some older JJ tubes in a pre-amp feeding a Parasound power amp. These seem to require a bit more warm up, and seem clearer on the bass than the JJ tubes. That's not a bad thing, as I think the highs are equally crispier through my AR speakers I can echo one of the other reviewers, they just seem louder all around. All in all, I'm impressed for the price. I wish I wouldn't have waited so long to change them out.

This preamp tube sounds very clear and nice but it has no low end at all. At least not for me. Stuff this in your amp if you have too much low end and want to balance it out, that is my recommendation.

I agree with the comments posted. I switched them into my 1987x after I dropped the bright cap down to a 400pf. I also coupled them with Mullard EL34's for the output. I use OD's with this amp so I can run it at moderate volume. It is a beautiful, bell like, crisp and punchy well articulated tone machine. I'm a EH12AX7 fan all the way.