Denon pre amp with Denon monoblocks

I have a two Denon POA 4400's and a Denon DCD 1420 pre amp. I am using the balance cables. All of a sudden today, my system went nuts. I am getting oscillating noise, even though it is still playing music. I am trying to figure out if it is the preamp our or something with the POA's. I have cycled power, and it is inconsistent whether it happens on both
Probably need to get new my mileage out these.