iMac 21.5" - power up chime but no sound once OS is loaded

[survivalbloke]

Have a 21.5" 2013 iMac here. Did a RAM upgrade and the oddest thing, we can't get any sound after it's booted. So Youtube, etc, nothing. We do get the startup chime though. In sound properties, all we see is the digital output. Did a little reading to discover possibly inserting a 3.5mm headphone into the jack would trip it back off the digital setting but that's not the case it seems. The headphone jack is verified connected to the logic board.

Any insights?

[reformatt]

Re: iMac 21.5" - power up chime but no sound once OS is loaded

PRAM reset?