Honestly you don't get a lot out of a tube rectifier vs solid state. It does bring plate voltage up slower, but thats really about it. You won't get any switching noise like you get out of solid state diodes but that can be easily eliminated with small capacitors across an SS diode. If you've ever had the hood up on your PL, you'll probably see those caps across the bridge rectifier for just that purpose.
I expect if you google it, you'll get stuff about voltage sag and all that. Thats more related to power amps, and specifically guitar amps. In a preamp, the load is constant (class A) so you should not have any sag problems. Thats not a desirable thing anyway, it adds distortion.
Which rectifier is it anyway?