This is a review and detailed measurements of the SONOS Connect Audio/Multi-room streamer. It is on kind loan from a member and costs $349 on Amazon including Prime shipping.The Connect has the look of earlier SONOS products which is attractive:Functionality takes a backseat to looks though as you get to decode blinking LED that can change its color. Better have the manual handy to know what it is saying.The back panel better shows the capabilities of the unit:The only inputs are Ethernet/Wifi and analog in. There is both Toslink and Coax and they are output only. This made my testing quite difficult as my Audio Precision analyzer cannot control such a device.Initially I fired up Roon and was pleasantly surprised that it saw the Connect and happily streamed my test signal to it. But all of a sudden it started to get errors talking to the box and I could not get it to work no matter how many times I reset/rebooted things.This forced me to use the Sonos App for all of my streaming. I find the app very poorly designed with hardly anything intuitive about it. Check this box for example that popped up as I was trying to configure it:So the speaker is added and I am being asked if I want to add the speaker??? Didn't a person with an ounce of common sense check this interface? And what are you supposed to touch next? The check box? Add a speaker, or not now? I hit the latter only to be taken back to start of the wizard.I am assuming once the company went public all the good people cashed out and are long gone....I configured the Sonos Connect for fixed output and played my 24-bit 1 kHz tone on the app and analyzed it as such:We have a bit over 2 volts output which is nice. SONOS specs the device at 0.009% THD+N and we are beating that by a good bit, getting a reasonable SINAD (signal over noise and distortion):Sigh of relief that it didn't end in the bottom red bucket of all DACs tested.Frequency response is pretty flat in audible band:Next I ran my j-test signal that is encoded at 48 kHz and got this:Good grief. What is going on here? Our 12 kHz tone is there but boy, do we have a mess of unwanted signals everywhere else.Guessing that this may be due to some really awful 48 kHz to 44.1 kHz sampling algorithm, I played a pure 12 kHz sine wave and got a much more reasonable output:This is very clean although the noise floor is high enough to mask a lot of sins.The owner uses the digital out from the SONOS Connect to an external DAC and wanted to know if that is an improvement. So I hooked up my Topping D50s via Toslink to the Connect and ran the same 1 kHz tone through the SONOS app:We get a 6 dB boost in SINAD but we are still at 98 dB whereas the D50s is capable of reaching up to 110 dB. The jungle of spikes including the one starting at 100 Hz tells me it is most likely truncating the 24 bit samples to 16 bit. With 16 bit, you can't get a SINAD higher than 98 dB.To confirm, I ran the Toslink output to my Audio Precision analyzer's Toslink input and measured that using the same file playing:We see that even staying in digital domain we can't do better than 98 dB of SINAD.So yes, you can get 6 dB of improvement with a better external DAC but a lot of the performance is left on the table if you play higher resolution content than 16 bits.I continue to be disappointed in the poor usability of the SONOS software compared to their early start where people would compare them to Apple when it came to design. Today, what I see is engineering driven user interface without any usability testing.I am also unhappy to see so many audio pipeline errors from poor sample rate conversion to bit depth truncation. Yes, most of their customers don't have or care about 24 bit audio. But don't they have any audiophiles in the company that care? Why not at least document all of this? It should take an audio analyzer and bunch of expertise and time to find out about them. Actually, I wonder if anyone has tried to properly test this device in the company to realize the butchered job here.On the good news front, the internal DAC has very good performance for its intended audience. 92 dB of SINAD is within shouting distance of ideal range for 16 bit audio. And if not, addition of an external DAC would get you there. Don't spend much on that though as you are only going to gain 6 dB so stay with under $250 DACs.The owner linked me to some vendor making a mod board to supposedly improve digital output jitter performance. Forget about it! There is nothing wrong with using the Toslink as is. Performance is not jitter limited. It is the 16 bit samples that hold it back.Bottom line, as long as you can avoid the landmines in configuration and signal processing, you should have very good sound both out of the analog outputs and digital.------Questions, comments, critique, etc. are welcome.Get this: the pink panther in the review picture came to me and says he wants to take dance lessons! Being a great dancer myself, I could teach him everything he would ever want to learn. But I don't have the time and instead need money to hire a dance instructor. So pleasemoney using: https://www.patreon.com/audiosciencereview ), or https://audiosciencereview.com/foru...eview-and-measurements.2164/page-3#post-59054 ).