I've gone from tube to SS on my phono pre-preamp. I wanted a quieter background, and I still have a tube linestage and power amp in the system. Interestingly, the sonic differences between various resistive loading options I tried with the new unit affected the sound much more profoundly than the switch from tube to SS with loading kept the same. Still, the sound was always more clearly delineated with the SS, the tonal balance slightly lusher with the tubes. The SS won on transparancy, resolution, solidilty and extension, even if it was a bit less voluptuous. When the loading was truly optimized with the SS unit, midrange tonality, HF air, and bass control were all more correctly presented, with fewer deviations from what I perceive as neutral, and focus was greatly improved. Not to mention that I got the noise reduction I was looking for, despite the welcome increase in gain. The units compared (using my B-M glider M2) were the phono stage of my C-J PV-8 preamp (47k ohm, 47dB), and the Camelot Tech Lancelot phonostage (set to 392 ohm, 54dB). The latter wins, even with the extra interconnects needed. At the low price, I'm not sure that tubes are as competitive here, but I haven't tried a premium tube phonostage.
P.S. - For those reading who have replaceable, socketed resistors for cartridge loading in their phonostages, I recommend investing in premium quality resistors once you have determined the correct value using the inexpensive kind. The Lancelot didn't come with these, but a couple of Vishay's did make a worthwhile upgrade for around $12 apiece; the $1 Dales sounded slightly colored and veiled in comparision (sorry to wander so far off-topic!).