Thanks Jac_Zar for the info., now I connected red wire to the positive (upper binding post circle in blue on the right side STA-9) and yellow wire connected to the positive (upper binding post circle in blue on the left side STA-9) and the black wire connected to the negative (the bottom binding post circle in blue on the left side STA-9), at the moment there is no hum sound.
Not sure if connect the REL to only one side of the STA-9, will there be any difference in sound, anyway will keep the mention connection for now, if there is any technical issue or caution about my connection now, please let me know, thanks a lot!