We recently added a new amp to the PA system and now are getting feedback. Using an Inter-Tel CS-5200. We basically split the line out from the Inter-Tel and added a new amp. The new amp is working as expected but, now the old amp will output a "tone" sound that gets louder the longer the port is active. Any suggestions?

Thanks in advance!!

I'd say to first check your "split". Then check your connection to the original amp. Make sure you're sending audio and not switching a relay instead. Test the audio to each location to make sure you are actually getting the audio.