Hi Larry,
I am using a Phillips Miniwatt metal base GZ34 in the rectifier position. What brands do you recommend in the EL37 and can you tell me how tall this tube is? I have a height issue on the power supply in my rack. I just recieved a pair of Rogers 6F6G's from Ecclectique. He told me that they come within a hair of the sound of the WE350b's. I have never heard the WE350b's, but I can tell you that he has never steered me wrong. I loved these tubes from the very first note of music. They are very detailed with good dynamics, a huge soundstage and very good resolution of the music. I also use GEC KT66's. In contrast, the KT66's are warmer with a little fatter, but well controlled bass. I like the KT66's for some nice slow jazz. My favorite thing about Mick's preamps is how you can "voice" the sound to your liking or mood just by changing tubes. God, I love this hobby! Just a note, my nieces husband is a musician and after hearing both the KT66's and the 6F6G's he felt that the 6F6G's came a little closer to the sound of real instruments (especially guitar).