Turn the amp on by itself and check for the hiss. Then turn on the 970. That should narrow it down. If the hiss is there with only the amp then check the connections on all of your speakers. If you are using bare wire make sure no stray strands are touching the cabinet or any others. If you are using banana plugs check those connections by reconnecting with bare wire. If the hiss appears when the 970 is turned on I would borrow some other interconnects and see if it makes a difference. If it doesn't contact outlaw for some help.