Looking for a tube preamp with remote control.

I like the idea of a passive remote volume control add-on.  The best, to me, are transformer-based volume controllers because they don't degrade dynamics (liveliness) as much as other forms of passive volume controls.  I like the Myemia control because it has a lot of steps to the attenuator (with few steps the "right" volume always seems to be between two steps), and it also allows for remote balance setting.  It is a little out of your price range, but, it is worth it.

http://www.myemia.com/Remote.html

The Placette RVC is a very nice unit.  Many years ago, I tried it in my system, but, I ended up buying their active linestage (unity gain buffer) because it sounded a bit more dynamic.  But, you already have a nice linestage, so the remote volume control makes sense.  

Don't stint on the interconnects needed to put it into the loop.  This level of gear warrants using really nice wiring.