You can, it works tiptop.

YES, but of course, the CD-NT670D is designed for this.
I myself do not operate it via MusicCast. Old style, too. But this will be my next expansion.
By the way, all functions work perfectly. I run my music collection via a NAS from Synlogi, simply cool.
A good investment!

Thank you very much for your answers.
The situation is too uncertain for me to spend CHF 457.

I use the CD-NT670D with a Yamaha Musiccast wx-030 speaker. You simply have to pair the two devices with each other in the app. It's been working since day 1, but I can't answer definitively whether it works with the newer speakers.

This question has never arisen for me because I have connected all devices via an amplifier.

No that is not possible