1) Box near a mic 2) Hi-fi component 3) Hi-fi element 4) Part of a studio system 5) Radio signal booster 6) Signal booster 7) Signal enhancer 8) Signal strengthener 9) Sound system unit 10) Sound-system booster 11) Sound-system component 12) Speaker booster 13) Stereo component 14) Stereo system component 
A signal boosting device
a preamplifier.