Airplay Yamaha CRX-N560d speakers working on iPad Air 2 but not on Macbook Pro 2017 Good morning everyone.

I own a Yamaha Net HI-FI, a CRX-N560D that has airplay capabilities.
I couldn't get my new Macbook Pro 2017 - High Sierra 10.13.3 installed - to stream audio to airplay speakers.
The Hi-fi is connected correctly to the router and then to Internet, as it streams Spotify flawlessly.
I had the same problem with my old Macbook Air late 2010 with every OSX i had installed on it, from Snow Leopard till High Sierra.
The odd thing is that i could connect easily iPad Air 2 since iOS 10...

The firewall is deactivated; no LittleSnitch or similar. There are no strange software installed, as i bought the Macbook Pro just yesterday.

Any advice or suggestion?

Thanks in advance!
Yamaha did release a firmware update in December 2017 and since you've been having problems with this for a while it'd be worth checking whether you actually have the latest firmware for your Yamaha CRX-N560D.

If your firmware is version 1.17 (or above) then you're up-to-date. If not then go to the CRX-N560D Firmware Update Version 1.17 page.