I saw those Gold Lion's myself the other day. Have to see if there's a couple of bucks in the cookie jar (left) and order a pair.
I have Electro Harmonix from The Tube Depot in now. They took a month or so to settle in, but sound good now. I have tried changing preamp tube, but really not been able to tell a lot of difference, a bit more smoothness in the old RCA I put in after trying a new EH. Hard to tell and even harder to describe.