Using Alexa to play music through your Echo and other compatible Alexa speakers is convenient, but if you have multiple speakers in your home, you’ll need to identify each speaker by name when you want to play music. To make things easier, you can set an Alexa Preferred Speaker that will automatically play music you request.
set acemax iEAST Oliostream 1 as preferred speaker in Alexa
Here's a growing list of some devices you can designate as your Alexa Preferred Speaker:
The Alexa app’s Preferred Speaker feature lets you designate one of your Echos or other Alexa-compatible devices as a “default” speaker. Once set up, you say “play music” or “play music from (artist or service)” and it will automatically play that music on the speaker you’ve chosen as your favorite for playing music, with no further identification required.
Here's an example of how to set up an Alexa Preferred Speaker using the Alexa app.