a driver tube recommendation for the Stratus
http://www.partsconnexion.com/tube_new_cryo_ss.html
I've had the Pearl gold grade cryo'd 6N1P-EV in my Stratus for a few days now, and I haven't had a single urge to remove it. Compared to the cryo'd RCA 6BQ7a that I had been using, the sound quality is definitely "mo' better", and by a mile. Richer, fuller, quieter, cleaner, completely detailed and dynamic -- just plain gorgeous. The main characteristic that appeals is the rich timbral presentation with chamber, a capella choral, acoustic guitar and jazz trio.
I did change 2A3s with it. The Sophia Princess tubes became too in-my-head. In contrast, the Shuguang Natural Sound 2A3C-T's project the sound image in front of my head (wow!), while maintaining the natural and extended tonality that the Sophia tubes excel at. Very cool. Not as solid as the EML solid plates, but just as dynamic. To my ears.
One additional note - I borrowed a bunch of Stillpoint feet, and I tried the mini's and the mid-sized under my Stratus. They produce a slightly cleaner signal, but also an audible suckout in the lower mids. The Marigo feet produce a greater coherence with no change in tonality, and if properly installed and adjusted, they earn a top recommendation. As I wrote here before, the rubber/cork feet on Fat Padz under the Stratus come close for way fewer $.