Phono preamp directly into amp?

You can use a passive pre if you can't find a phono stage with volume controls; most passives don't have balanced outputs. I think the Manley Steelhead phono stage might but I haven't used one.

the PS Audio has gain (volume) control. I have one that was modified by Parts Connexion and it's absolutely stellar. It beat out many more expensive phono pre's and stayed in the system.

You'll of course need a phono amp. You didn't say what Wadia unit you have, nor is your system posted. But if your Wadia has digital inputs, I'd recommend a high quality analog-to-digital converter (like the Wadia 150) to receive the output of your phono amp and you'll be all set; and without the need for either a Bolder ($$ ;--) preamp, or a more expensive (and probably noisier) phono amp with volume controls.

Manley Steelhead - Has an extra input for your Wadia