In JRiver playback options I have the irDAC selected as the audio device with integer mode activated.
Integer mode can be a little bit finicky. On OSX El Cap, it doesn't seem to work with many DACs at all, even those that worked on previous versions of OSX. This is just some extra information since you mentioned it.
To address your questions about sample rate and output format:
Here's how it works: MC knows the sample rate of every file. It will try to play those files *at* their native sample rates by default. So it will sent 44.1kHz audio to the DAC when you play a 44.1 file and 96kHz audio to the DAC when you play a 96k file. If your DAC doesn't support some rates, you can use DSP Studio's Output Format mapping section to change some sample rates into others. For example, my DAC can't play anything above 192kHz. So I set every rate *above* 192 to translate down to 192. That way I can play 352.8kHz audio; it just gets resampled by MC down to 192kHz.
Audio MIDI won't need to be adjusted during playback. MC will indicate to you what sample rate it is sending in the Audio Path. Player > Audio Path . (Or hover over the blue light next to the shuffle and repeat buttons at the upper right of the window).
If you look at Audio MIDI while something is playing, it should show that it has adjusted the output to match. EG when 48kHz is playing, Audio MIDI will show something like 48,000 Hz, 2 ch, 24 bit .
So you should be fine. As long as that DAC is known to work properly with OSX, MC should drive it properly.
Brian.
