I purchased the Volumio Rivo and LHY 5 volt linear power supply from Beatechnik.com. The Rivo is optimized for USB output and does not have an i2s output so I bought it to pair with a usb dac. You definitely want to get a power supply to use with the Rivo.The LHY LPS is inexpensive, very well built, feels and looks solid, and works without any issues. Rivo's design and operation are elegant and simple. The Rivo was extremely quick to set up and connected seamlessly with my network. One of the selling points is the Rivo runs on Volumio software, and it comes with a lifetime subscription to Volumio Premium. The Volumio app looks great and I'm finding it easy to navigate, with many options available for listening. The integration with Roon, Qobuz and Tidal has so far been flawless.
I bought the Elemenent S from Power Holdings. The Matrix Element S is a high quality streamer that looks great and has a lot of features, including a display. The remote app has been greatly improved, and now works well with Tidal and Qobuz. At times I have issues connecting the Element S to the network, but ultimately it always ends up connecting.
Both Volumio and Element S are Roon Ready, and connect via wifi and lan, and have options to connect external media with music files. The Rivo outputs 384kHz and 256 DSD, while the Element S outputs 768kHz and 512 DSD. Both streamers are able to stream music in a very balanced and precise way and bring a full, effortless and smooth music presentation to any system. Vocals and instruments are lifelike and natural. If pressed, I'd say that the Element S soundstage is wider, and detail retrieval, imaging and instrument separation are a bit better. However, both produce a rich, musical soundscape.
If you plan to use the streamer with dacs that offer both usb and i2s connections, and like a streamer with loads of features and a display, I'd go with the Element S. While the Rivo is a solid, very reliable streamer with an awesome app, I'd give the edge to the Element S. Matrix makes has a lot of experience making excellent audio products.
Hope this helps.