Battery powered mic preamps, headphone amps & combo units:

Sound Devices

• MP-1 - Single mic Preamp
• Mix Pre - Dual mic pre /mixer w/ headphone amp
• MM-1 - Mic pre / Headphone amp (standup or boom position)
• HX-3 - Mono /Stereo 3 output stereo headphone amp

Whirlwind

• MD-1 - Mic / Line preamp w/ Headphone Amp

RKR Micro

• HP 1x3 - Mono /Stereo 3 output headphone amp