Thanks. While I did mention this failing, it is not uncommon and not a big deal, just an inconvenience. What is a big deal is the MacMini's inability to output any audio with a sampling frequency higher than 96kHz (or with DSD) over HDMI and the Gefen box (according to the user's manual) has no EDID that does better either.

FWIW, upgrading to the new OS, Yosemite, makes no difference.

Is there any possible solution to connect HDMI input and output ? I want to learn more about it.

I have boot-camped my MacMini and cannot address this directly. Even under Win7, there is the same HDMI constraint. However, now that I am using a USB DAC with the MM, turning the HDMI display on/off has no effect on the audio output. Strangely, I tend to leave it on anyway.

All:

I used to be a software engineer for Verizon Enterprise for 15 years..UNIX and Windows C/C++ programmer. I know one can "hack" an EDID file...perhaps manual entries can be made for higher frequencies?

I have in fact successfully done this on UNIX for monitor refresh rates. The only caveat is the hardware has to be able to handle it, as well as the firmware and drivers.
If someone feels like looking up the audio specs for the exact mac mini in question, I can try it out on my MacBook Air for grins. Or, Kal, reply with your model of mac mini and I'd be happy to look it up. I would need the year and time of year produced. For example: "Early 2012 Mac Mini".

After a quick Google, here is an excellent article that backs up what I suggested:

http://darkfader.blogspot.com/2012/06/edid.html

Just a serious suggestion.

Respectfully,

Ron