This paper introduces the external switching buffer module which is a newly custom designed for HVMU 2.0 instrument direct path. Despite the instrument’s robust performance, it suffers from channel count limitations within a single slot configuration. The conventional approach of adding external relays on the PCB surface is insufficient due to issues related to isolation from relay power noise and susceptibility to electromagnetic interference (EMI) induced by high voltage switching. Also, its fixed 50ohm termination input condition could not be guaranteed by most Rogoski coil suppliers for full range peak performance. As an integrated solution, this module is designed to solve those problems at once. This module incorporates an impedance-changing buffer with external relay switching input and it offers a standalone +/-14V clean floating power source isolated from the common DIB supplies. More interestingly, this module is shielded by full metal cover for both sides, top and bottom. It is then assembled with specially matched plastic components to provide the best possible noise immunity.