Shure SCM268 4-Channel Microphone MixerThe competitively priced SCM268 microphone mixer features six transformers inside: four transformer balanced XLR microphone level inputs, one transformer balanced XLR mic line output, and one internal low stray field, toroidal power transformer. Many Benefits, Little Space All those audio transformers provide protection from RF interference, prevent ground loops, and make the SCM268 exceptionally quiet. The internal toroidal power transformer means