I also had a problem with the Niles Si 2150 in a sonos system , and I had the gains on the Niles set to 11:00. The amps go into protection at half sonus volume. I am running 1 pair of 8ohm speakers, there is no reason for these amps to go into protection. This has happened of a few occasions with different Niles Si 2150 amps. I have also used Parasound in the same system with no issues. I would say stay from the Niles Si series if using Sonos.