You might be able to find one of our used MP-3s in that price range; it would do the job. How its different from most high end audio balanced preamps is it has a direct-coupled output, and supports the balanced line standard, otherwise known as AES48, which most tube preamps don't (and a lot of solid state preamps for that matter).
AES48 reduces the liklihood of ground loops and also the artifact of the interconnect cable itself (if you've heard the difference between two interconnect cables in audition then you know what I'm talking about). Most preamps don't support the standard since an output transformer is usually needed (the Backert Labs Rhumba has an output transformer for balanced operation, so should be a contender here). We patented a means of direct-coupling a balanced output. Getting rid of the coupling cap at the output means greater transparency and bandwidth.
AES48 reduces the liklihood of ground loops and also the artifact of the interconnect cable itself (if you've heard the difference between two interconnect cables in audition then you know what I'm talking about). Most preamps don't support the standard since an output transformer is usually needed (the Backert Labs Rhumba has an output transformer for balanced operation, so should be a contender here). We patented a means of direct-coupling a balanced output. Getting rid of the coupling cap at the output means greater transparency and bandwidth.