We are using the new LR Baggs IBEAM Active System (Classical). It is a combined pick-up and pre-amp with a 1/4 inch jack connector. This pick-up is specifically voiced for nylon string instruments and has a high degree of fidelity which will bring out the dynamically rich voice of your Rees Concert Line Harp. The pre-amp is also specifically designed to add a bit of compression and auto-EQ to render a warm, analog voicing without the need for an additional EQ board. The IBEAM Active system is powered by a common 9V battery.