Hi @yardbird and @JLM --
I have an SHD, the full one with DACs.
The SHD Studio does not have DACs. The plain (full) SHD has four channels of DAC, good for someone who want to use it for mains and subs, for example.
As you said, the music player built into both models is Volumio. I believe you do have to pay the fee for MyVolumio (Volumio's expanded offering) to use Qobuz through it, but only if you are using the Volumio interface. If you are using the DLNA/UPnP interface to Volumio, you can use BubbleUPnP on an Android device to send Qobuz to the SHD without paying anything more than the Qobuz subscription. That's what I do.
I suppose (but don't know for a fact) that there should be iOS apps that do the same thing. In short, any app that can send a Qobuz stream to a DLNA/UPnP renderer should be able to send Qobuz to the SHD.
The Qobuz desktop app I have (on Windows) also has a beta-test DLNA setting, but I've never gotten it to function. Apparently, it is a very low priority for Qobuz.