Hi @Carlton8000 

Welcome to the Sonos Community!

I don’t have any experience with Meridian, but I can tell you that you would be able to control the volume from AirPlay, the Sonos app, or the third-party amplifier.

As for digital attenuation, that refers to the actual digital stream’s signal on the cable, and not the volume which would be encoded within the stream. However, I don’t believe you would be able to turn up the volume beyond that which is set manually on the amplifier’s controls, only lower it - full volume control would only work with devices bearing the Works with Sonos badge.

I hope this helps.

Your MERIDIAN will accept PORT as a miscellaneous analog source, such as a CD player or cassette deck.

So are you saying something such as an Meridian 218 (awaiting delivery) will not work properly using the digital output from the PORT?

I could not make out quite what this 218 is? Just a preamplifier of sorts, supplying to an external power amp?

I did see this for it though, on the feature list, so you should be ok!

WORKS WITH SONOS
Seamlessly stream music from the Sonos app to a Meridian system and control the music from anywhere around the home using the Sonos interface. Works in conjunction with the Sonos Port or Sonos Connect products.

In the case of AirPlay 2, I expect that App would digitally adjust the level sent to Port.

You’ll need to fuss with things and work out a Volume control strategy because each item in the chain would like to be in charge. AirPlay 2 — PORT — 218 — amplifier. I would start by setting PORT’s output to “fixed”. This will eliminate one level control in the chain. Likely, you’ll be able to set and forget the amplifier level. This will leave AirPlay 2 and the 218 to fight it out.