Who or what is Sonos?

Search engine shows "Sonos" as an internet connected speaker (Alexis, Pandora, etc).

There are many different generations and models of Sonos speakers. It's like asking what tires you need for your Toyota. Which Toyota model? Year? Engine type? etc.

Not all Sonos speakers have a line in - but you're going to need it if you're going to connect Montage. Montage is not a wireless or internet connected device. I suppose since Montage is an audio interface and you can use this feature to get Montage to play its audio on a PC - you could go through the hassle of streaming Montage using a PC with some form of media streaming application. But this would get unsatisfying in usage, long winded, and complicated. There would be a large delay between striking a key and having sound come out the speakers.

For Sonos models with line in, follow Sonos instructions.

https://sonos.custhelp.com/app/answers/detail/a_id/1091?_ga=2.79881232.686735686.1518113531-2098578510.1518113531&_gac=1.16410114.1518113531.EAIaIQobChMIzaf4t_WW2QIVySWBCh1ocAIxEAAYASAAEgIT5fD_BwE

You're going to need an adapter cable between the Montage Main L&R outputs - 1/4" TRS (or TS - TS is all that is needed here since you're going to loose a lot of fidelity using Sonos's line in). There is no telling if your speakers have a line in. Check your model vs. the list or look in your Sonos manuals.

Yes, I can Google Sonos, but that does not tell us that this is what the poster is referring to...

The output level of your MONTAGE is considered a “LINE level” Signal (-6dB, 0dB, +6dB, +12dB) please do not just adapt the cable to make it fit. When you find yourself *adapting* you should ask why the device doesn’t have the inputs I need. Could be because it is trying to prevent you from plugging LINE level signals in and perhaps damaging your system. Check with the makers of your Sonos system. You want to ask about the INPUTs and the Input Sensitivity. I’m sure in whatever Owner’s Manual that was included does not show a music synthesizer connected to the system - so it’s worth contacting them.

You know what Sonos is, contact them and ask what happens when you plug a LINE LEVEL signal into them or if you even could. They will either tell you “no way” or what you should do to prepare the signal for their product. The MONTAGE would survive in the worst case scenario.... a consumer speaker system might just send up smoke signals!

As an owner of Sonos equipment and a few synths I'd advise against trying to play your keyboard through the Sonos system. Whilst it's probably technically possible via the Sonos hardware that have line inputs, I'm 99% certain that it will introduce latency and so there will be a slight delay between you pressing the key and hearing the sound. That would be unacceptable to me 🙂

For live audio latency introduced would be bad. For recorded (without also trying to "play along" with the same keyboard) latency would not impact the experience. It's hard to tell for me if the product has a "line in" on the transmitter or directly on the speaker. I'm not sure if there are models with no "base unit" where the "smart" part of the speaker is integrated with the speaker itself. If such models exist (with no separate transmitter) - and the OP has one of these - then the "line in" should be direct without going through high latency paths.

It's shooting at the dark without the requested additional information.