How about an EQ pedal? It'll give you any kind of boost you want.
The only "color" it adds is whatever color you want (or none at all, just a flat boost.)
I like the analog JHS Colour Box. FULL CONTROL over my tone with plenty of boost through variable gains stages. Also acts as a pre-amp pedal in a pinch.
Also you can't go wrong with the Source Audio EQ2, it's the best for versatility, and it's used on many pro players boards.... Outstanding quality sound and control.
The Empress ParaEQ is best if you want an analog parametric EQ/boost.