I can hear a hum coming through my loud speakers
20
Input sockets and/or output binding posts corroded
Check that the input and output RCA sockets and binding posts on the rear of the SX25 are free from corrosion.
Interconnect cables damaged
Make sure that the integrity of your interconnect cables is sound and they are firmly connected to your source and the SX25.
SX25 is close to external interference
Check the proximity of your SX25 to any possible source of EMI and/or RF interference, for example computers, televisions, amplifiers, speakers, etc. Ideally the SX25 should be placed as close as possible to your source.