Hi @cinco 

Welcome to the Sonos Community!

Please reboot the Port by removing power for 10 seconds or so. While waiting, please check each connection of the audio cable at the Port end, and at the amplifier end.

If you have a spare audio cable of the same kind, please try with it instead.

Test, and try to reproduce the issue. If the same thing happens again, please immediately submit a support diagnostic and reply here with the number given when convenient. 

Thanks.

I changed cables and unplugged port no change fuzzy sound .

cinco 

So, did you submit that diagnostic immediately, as @Corry P suggested? He’ll need you to supply the number to him, so he knows when/where/what to look at. 

I don’t understand what number and diagnostic ?

Did you click on his underlined link? That would explain how to both run a diagnostic, and to get the reference number it generates.

Have you perhaps tried switching the Port’s Line-Out between ‘Variable’ & ‘Fixed’ volume modes, to see if that makes a difference (just ensure the NAD Amp volume is set to low before making the settings change, so that it doesn’t suddenly blast any playing audio out your speakers).

@cinco,

If playing audio from the Port’s Line-In also perhaps try setting the ‘Source-Level’ in its room settings to a higher value (perhaps between 8 and 10) - to suit your own preference.