I have three different tube sets for each area of Jim White's Aesthetix design. Stock Sovteks of course for everything and they were pretty good. I am doing this from work right now and don't have the exact facts in front of me right now. Please feel free to E-mail me directly if you want the exact specific brand and tube types. So go easy on me if I am misspelling the brand names in the following tidbits. Still going from my memory the preamp section I got NOS Mullard and Mazda special selects. For the PS I got extra Mullard EL34s and then went to Genelex KT-66s. Jim White can customize the pre-amp area to accept two power supplies. Note the standard product has one very hefty separate power 19X22X6 supply. With Jim's mod you then get to add another one just like it for even better power supply reserve, regulation, and lower noise. How much does this really helps - is subject to your interpretation of the final results. Jim is very happy with the standard product, as he has designed. I like the tube changes that I have dove and adding the extra power supply. BTW: Albert Porter was great in helping and suggestion way to change the sound. He really knows the sound of many tubes. Also, Ken at Upscale Audio was extremely helpful on tubes sound characteristic and getting me great NOS tubes. Hope this helps. Also, Jim White was very responsive and treated me very well even when I did a dumb ass thing like having a wrong tube type in the wrong place. Amazing that it worked at all. BTW: do e-mail me, because I want to continue the good practice of assisting others that people like Albert Porter practice on this site.