JPlay odes not officially support use with Jriver.
JPlay Femto server does not work but the JPLAY Femto players works well with JRiver and in my system is a noticeable improvement in SQ. this is considering that JRiver is already a very good sounding platform
I have JPlay Femto and definitely like it; I get obviously improved sound quality vs both Foobar via JPlay and JRiver alone.
I currently connect to my DirectStream to PC with an AudioQuest Diamond USB and was thinking of upgrading to the Bridge if it were a “JPlay” alternative, so I had OP’s same question in mind… glad to see I’m not alone.
My motivation behind thinking about the Bridge is that I previously owned a Bel Canto DAC 3.5 and REFLink combo; using a fiber optic to connect the DAC3.5/REFLink was noticeably better than my AQ Hawkeye SPDIF, which I always assumed was because of increased electrical isolation between the components… since the Bridge would presumably offer better electrical isolation than USB, I was thinking improved sound quality would likewise follow…
While I don’t get along with JRiver’s interface very well it does have really good sound quality. I find the Bridge II to have better performance than JRiver through USB into our DAC. I find Audirvana to be just slightly better than JRiver in performance and approaching that of the Bridge.