12AT7 tube replacement : Genalex 12AT7 Gold Lion sonically better than JJ ?

Hi, I am contemplating to replace the stock JJ tube with Genalex Gold Lion for my Preamp ;just wonder what   the sonic benefits/upgrade would be. I need your opinions.experiences and suggestion. Thank you 

Go for it. More detail, air, less warmth. Give it a few hours to open up.

Thanks noromance ! How about the Bass ? Is it better than the JJ ?

I hope the overall sound would not become leaner or thin and too-analytic

Should be fine. Hey, it's only one tube. If you no like, maybe you can return it. Whatever you do, live with the new tube for a while before making a decision. Welcome to tube rolling. I have scores of tubes that didn't make the grade.