LTA MicroZOTL tube upgrade

I've got the latest microZOTL; I liked the stock 12SN7's. What I did need to change though were the stock 12AT7s - they were really holding the sound back to the point where I was ready to send back the preamp during the trial period. I told Jacob at LTA and he sent me a few alternatives to those, and 1 of them, tall Dutch Mullards, did the job perfectly and I'm very happy with the preamp now. 

@larsman I have Mullards 12AT7 so probably the same they sent you.

I’ve read several positive reviews of Genalex Gold Lion tubes, especially for rock music.

I move between two sets for mine. The 1960's Mullard CV4024 absolutely added warmth and density for me but the original stock for mine was not Mullard, was Gold Lion which were anything but warm. I also have some Telefunken 5965 longplates that are just a bit less warm but add some exceptional detail. Mullard, at least their NOS tubes, are kind of known for warmth and depth so you may spend some $ and not get a lot more.