There is a delay, but it’s much, much smaller than the 75 ms. Nothing in this world is instantaneous. ;)

And unless your DJ board creates an HDMI ARC signal, this won’t work. The Sonos requires the signal to be on the ARC channels, not the standard HDMI audio channels. You could potentially feed the signal directly to your TV, which then would reflect it back out to the Sonos. So your switch would be on the TV’s input, and the Sonos on the TV’s ARC output, which means the TV must be on whenever you’re attempting to use this setup. 

But I’m not willing to guaranty satisfaction here, in terms of functionality. You’re going a long way to attempt the use of Sonos for something it’s not designed for. 
 

Oh….as soon as you ‘group’ a second room to the ‘room’ that is that Amp, to extend the audio to additional speakers, those additional ‘rooms’ will have that 75ms minimum delay. 

Attempts to get Sonos to do things for which it was never designed generally end in tears. I agree entirely with Bruce's analysis. I think you should save yourself some grief and, in the long term, money. Enjoy Sonos for the things it is designed to do and get a different, single speaker for the DJ-ing.

Thanks for the thoughtful responses, makes a lot of sense that trying to hack this so it fits an unsupported scenario isn’t going to end well!! Can totally see myself buying a lot of connectors and looping things through the TV etc, and and up probably still having an experience that doesn’t work properly, or at the very best is super awkward to use...

Appreciate the insights and advice. Think I’ll go shopping for single speaker as you suggest John.

Hi @jossick 

Welcome to the Sonos Community!

Quite a few people, like yourself, want to use Sonos equipment when DJing, so I thought I’d add a few details here.

Internally, Sonos works with digital streams - we utilise digital amplifiers, so it’s only at the amplification stage that the stream is converted into an analogue signal to be fed directly to the speaker drivers. It’s done this way for the purposes of grouping and syncing the music across multiple rooms (and because online sources/local files are already digital in nature). Therefore, any analogue signals - like those coming from a mixing deck - must be converted into a digital stream and this always takes a little time. This makes DJing well on Sonos a difficult thing to achieve - as in, sure, you can do it, but good luck being able to match the next track to the beat!

HDMI, however, is a digital interface, therefore any audio feed coming via this type of input is already going to be digital, by definition. Therefore, Sonos Home Theatre devices can play these streams relatively instantly. But, any attempt to transfer an analogue feed onto an HDMI cable is going to, at some stage, require digital sampling which is going to take some amount of time, again. The only way to get around this is if your DJ deck is willing to output a digital stream via an optical digital output, which can then be connected to using the Sonos Optical Audio Adapter - I don’t know if any mixers actually do this (I did a quick search and didn’t see any), but some do offer USB output, so perhaps a PC could take this and Passthrough to it’s own optical output? Please be aware that this is all off the top of my head and I have no idea if it would actually work, but it’s likely the only way it’s ever likely to do so.

If you are using DJ software, rather than a physical mixer, you’re much more likely to be able to get the stream onto Sonos via HDMI (again, via optical first - don’t connect Sonos to an HDMI port on a PC) - it just depends on if the software allows it. I don’t see why it wouldn’t, in principle.

Personally, I agree with @John B - just buy an analogue speaker/amplifier. But, if you’d like to test your cheaper options first, I hope this helps.

It’s been rightly pointed out to me that it is the buffering that Sonos performs after the digital conversion so that multiroom playback can be synchronised that induces most of the delay experienced when playing Line-In sources, and not the digital sampling as I mentioned. Sonos Home Theatre devices do not pre-buffer HDMI inputs prior to their own playback as playing TV inputs to multiple rooms isn’t supported (because of the delay that buffering induces) and that’s why the latency is considerably less.

This doesn’t affect any of the possible resolutions listed - you’d still need to avoid using the analogue Line-In. It’s worth keeping this lack of HT buffering in mind if you do get it working - grouping may work, but not necessarily reliably.

Thanks @ratty