I just received the new Denon AVR-3700H and everything has been decent except for that I cannot get either of the digital coax inputs to work.\n\nTL;DR: I'm wondering if someone with an AVR-3700H could check to see if the digital coax inputs work for them.\n\nI have the receiver connected to a computer and normally I use HD audio via the HDMI cable which works just fine, but I also want the option to use my pro audio soundcard's digital coax output for low latency purposes (noodling on soft synths and guitar amp sims).\n\nI know for a fact that the computer's digital coax output works and that I have the receiver's input routing configured appropriately (digital coax 1 source, digital). As a sanity check, I used a cheap little digital to analog adapter, and connected the converted analog outputs from the computer to the receiver, and it worked after configuring input routing accordingly. I also tried using the computer's onboard digital coax to no avail. However, the PC's onboard soundcard's optical digital output worked. So that's good to know and all, but I need to use the digital coax from the pro audio card.\n\n \nI updated the receiver to the current firmware. One thing that struck me as odd was that when I went into the setup menu to configure the TV audio output setting, the UI would freeze for a good 2 minutes and only the optical digital option was listed. Eventually, the UI would start responding but there was still only a digital optical option. The TV audio menu seems like just a dumbed down helper option that is also covered by configuring the input routing settings, but I figured I'd make a note of these findings.\n\nI just got off the phone with Crutchfield support, and as a last resort we did a full reset. Interestingly, after that, when I went into the TV audio settings, digital coax and analog were listed, but unfortunately I could still not get audio to play over the digital coax input. I've also noted that the receiver does display PCM DIG on the LCD when playing digital coax audio and the indicator goes of when unplugging the cable, so it's like it does see the signal, but I get no audio. Crutchfield is sending out a replacement unless they discover something new in the meantime, but the receiver is back-ordered for a couple of weeks.\n\nIt seems like something's buggy to me, but I haven't found anyone else reporting the issue after scouring various threads, but this is pretty new equipment and I have a somewhat unique use case.