Also haven’t heard it, but the Volumio Rivo is supposed to noticeably improve upon Eversolo in sound presentation. It uses a Khadas type cpu. The only thing is that you’ll need to get into using Volumio OS, which is actually really good. Lots of helpful plug-ins and sound options, mist very effective and useful. You’d also get a free subscription to their top tier version of their software if you purchase one of their in house streaming devices.
I’ve currently got a Pi2 design Mercury streamer using Volumio and think it still sounds very good - but am also considering an upgrade. I was looking looking at the Eversolo masters edition, until the Rivo showed up. Only possible dealbreaker, I don’t think Volumio supports Amazon music? But I do know Qobuz sounds exceptional through this software (as does Tidal). Band amp is also available through the plug-in section, also sounds great.