The Cocktail X40 is a pre-amp, music hard drive (on which I've stored lots of CDs - which you'll get - but you can delete if you want) and, most importantly, a wireless or cabled (I've run it both ways) streamer just like a Sonos Port or WiiM Pro Plus Streamer. You control it through the MusicX Neo app on your phone and stream your Spotify, Tidal etc or listen to streaming radio (BBC etc) or your stored CDs. I've run it connected to my amplifier and it sounds fantastic. Very simple to set up to your wifi network and your other hifi equipment. Have a read of the reviews https://www.cocktailaudio.com/home/sub01_03.php and https://www.soundstagehifi.com/index.php/equipment-reviews/850-cocktail-audio-x40-music-server. In very good condition. I bought it from Sound Expression in Wellington 7 or 8 years ago. The downside is that the app is clunky and not as user friendly as Sonos or WiiM. So while I've been fine with that app my wife and daughters haven't - they just prefer the Sonos interface.
If you're looking for a Sonos Port to connect to your amp, then this will do the same job - plus give you all the storage. Priced to sell as I don't want to leave in the cupboard.
Dimensions 44cm x 10cm x 33cm Pick in central Wellington (Oriental Bay) or will ship in an amplifier box.