we need more information.
from your use of "PA" I assume you are
intending on hooking up the preamp to a sound reinforcement rig. keep in mind this is a TOTALLY different thing than a recording setup. please be specific about the kind of equipment you have.
if you currently have a mixer to which you can hook up a microphone, you do not need a preamp. IMHO if you want to improve the sound of your vocalist, either get a new one OR invest in a high quality mic and mixer. this will have a greater effect on the sound you get than the proposed "Tube mic pre" and keep in mind the lower-end tube units can be noisey.
[This message has been edited by Take5 (edited 07-24-2000).]