Hi Scott, Nice work. I've been curious about the kt90's. I do not have enough experiance with guitar amps to know if the posieden would get the sound you want. I do know that I don't like the sound of the 6AN8 in hifi applications. I'm sure someone around here would know. Did you get your chassis & cage from antique audio? I bought from them too & they do have high shipping & handling. My chassis are hammond, they are ok, but the spot welds show. Another good supplier is
www.mouser.com Great for resistors,caps,terminals,boards etc. Kimbob