I have just installed J River MC17 and stream to an Oppo BDP 95 without any problems with FLAC & WAV files. No problems, that is, with 16 bit/44.1 and up to, and including 24 bit/96 kHz. However, when I play 24/176 or 24/192 files, it stutters at the start of each track for about 4 - 5 seconds then it plays normally. Occasionally, about once per album, it will also falter mid-track for a few seconds.
I am not sure if the problem is with the Oppo unable to buffer such large files or the MC17 software. I am using WASAPI - Event style, "Never Convert", "Uncompressed", sample rate "Same as Source" and 24 bit depth in DSP Studio. I have tried every "Hardware buffer size" buffering setting from 10 to 500 ms but it made little difference when it came to the file over 24/96.
I am disappointed that I am so close, but still having problems. I could always give up and use a USB cable between my laptop and the Oppo input, but I would rather DLNA stream as it is more convenient.
But to answer your problem, I have had no problems streaming FLAC up to 24/96 using MC 17 with the Oppo BDP 95.