a second amplifier configured for amplifying {HEAD ~ the data} received from the second I/O port and outputting {TAIL ~ the amplified data} to the first I/O port 
a second amplifier configured for amplifying { HEAD ~ the data } received from the second I / O port and outputting { TAIL ~ the amplified data } to the first I / O port
OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH