Lots of the members with four-to-six-figure systems use Roon for its interface. They tend to congregate in the high-end section of the forum.
Here is a thread about Roon: http://www.head-fi.org/t/766454/roon-is-live
I'd wager that it sounds the same as JRiver if you are using bitperfect output. But some couple Roon with HQPlayer, which does DSP to (arguably) achieve higher fidelity audio.
Forgive me but I haven't used either roon or hqplayer but what do you mean by they couple these two players together? Do you mean they connect the two or sometimes they use one or the other.