{HEAD ~ The low frequency amplifier} 304 is typically {TAIL ~ a switch voltage supply}, in which one of a plurality of fixed voltage supplies is selected in dependence upon a current input signal 
is typically
{ HEAD ~ The low frequency amplifier } 304 is typically { TAIL ~ a switch voltage supply } , in which one of a plurality of fixed voltage supplies is selected in dependence upon a current input signal
HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH