The ProJect Pre Box RS2 Digital is a balanced preamp with a selectable tube output (or solid-state if not selected) with multiple selectable filters, a headphone amp, and dual DAC (ESS Sabre Pro 9038). It has a small form factor. New it is a little more than your spending target, used, a little less.
The Schiit Freya+ is a balanced preamp with selectable tube section (giving 12dB gain) that uses 6SN7 and other octal tubes or available solid-state LISST octal modules in its tube section, It has also a buffered solid-state output section and a passive no-gain section. Its form factor is table-top, due to the tubes extending partially out of the metal housing. Price new about $900, used less, excluding LISST or tubes, which are additional.