The one other issue with tube phono stages (or tube preamps in general, actually), is having to determine if they have enough output "drive" to supply enough good signal, to the typically-lower input impedance of a solid-state (or some modern-manufacture tube) amp.
Most tube devices have an input impedance of AT LEAST 100K ohms, and many are 200K ohms or higher. To contrast- it is not unusual at all to have a solid-state amp with a 47K ohm input impedance- and a non-trivial number are 22K, or even 10K ohms.
Back in the old days, when everything was tube, it was a reasonable assumption that any amp a preamp would be used with, would have higher input impedance. But, with the introduction of solid-state amps, these assumptions are no longer valid! If the output of the tube preamp is NOT set up to PROPERLY deal with this low impedance, there can be quite significant issues with gain loss, compression, and even outright distortion, when tube preamp gear is used with more "modern" SS (and even some modern tube) amps.
To properly deal with this, a tube preamp device should be BUFFERED on the output. Usually, this means a cathode follower or other low-impedance device at the output, to drive the following amp. Regardless of how it's done, though, there HAS to be a low enough output impedance, and enough current/voltage capacity at the loads that COULD be seen, to make sure that the preamp can still drive the amp!
That said- if you have a phono cartridge with enough output (5mv or higher) so that the preamp doesn't have to have a "zillion dB of gain" (they can get noisy when a lot of gain is needed, such as with a moving-coil or other low-output cartridge)- a tube phono stage can sound VERY good. I have gone back and forth, and wound up using a tube phono stage with my Ortofon 540Mk II cartridge (predecessor to the excellent 2M Black- probably close to 7mv output at max modulation!). I've had this setup for 5 years, and never find any reason to change it...
In any case- just be sure to make SURE, that whatever preamp you use, is properly suited to drive whatever amp you use it with!!
Regards,
Gordon.
