To the first post, 24 bit and 16 bit make a difference. It did on my laptop using foobar and changing the foobar setting from 16 to 24 and back. It's subtle, but it's a definite difference in soundstage presentation (24 bit providing a wider, more blended soundstage.
To the second post, I completely understand the the selection of devices with regards to output. My question surrounds the INPUT device selection and it's ramifications on the OUTPUT stream. Let me put it this way, when the Audio Midi "Properties For" is set to "Output Device, Benchmark Dac1", it puts out 24/44.1. Further, the DAC1 WILL NOT go into sleep mode when the computer is put to sleep (and at times it won't sleep when the computer is turned off). Now, when the Audio Midi "Properties For" is set to "Internal Input Device" and you change the settings to 16/44.1, the Dac1 responds with a different sound which to me is for all appearances 16/44.1, and further, the DAC1 will go into sleep mode when the computer is put to sleep. Also, there are no "properties for" settings for output when you select the built-in input settings.
The crux of this is I believe Macs are set to both receive and put through digital streams. I wonder if the Mac is locking it's usb output to 16/44.1 when you select that for input, as the two are communicating to one another. To me, it sounds bit perfect.
And again, there is a difference between 24/44.1 and 16/44.1. A definite difference. And it sounds incredibly clean with no distortion, so I'm inclined to believe both are bit perfect.
I've looked for info all over regarding this, but there's not much out there regarding interaction with Audio Midi and DACs, even on the benchmark website (they seem to contradict themselves depending on what version of Itunes you use, which is understandeable given the changes from version to version).
To the two prior posts, I do appreciate your input, sorry if I seemed dismissive, but there's a definitive difference between the 16 bit and 24 bit settings, almost as if it's putting the DAC1 into NOS mode.