96K audio output brighter than lower bitrates?

[Escher2112]

If you are a member over at AudioKarma then this will be a repost - sorry... but I'm stumped:

Just FYI - Here is my signal chain:

MacPro (2008) --optical --> DEQ2496 --coax--> DAC--analog--> Carver C1 --> Carver TFM25 --> MGII

So - when I play flac files, in any application... and I switch from 44.1K to 96K in audio/midi setup, its like someone *cranked* the treble knob... Its a lot brighter at 96K.

Source files have been 44.1 and 48K.. so the Mac is upsampling to 96k..

My DAC is a 24/192 diy kit I got of the 'bay a few years ago its got decent specs for the D/A (PCM1798)...

ideas?

I'm running 10.9...

 

[psycho bob]

As silly as this may sound, what makes you think the mac is up sampling to 96KHz? Just because the output has altered to that setting I would be more inclined to think it is outputting in the original format with a lot of headroom or doing something screwy and actually shifting frequencies.

Up sampling is a specific function and in terms of hardware I doubt any mac supports it natively. As such you would be best off sticking to the native format and looking at sampling and converting in a single device. I don't know the specs for the audio boards in your mac but I suspect it is digital out only without conversion. Maybe software solutions exist.

As for why it sounds brighter I know not but it would indicate that something is amiss.

 

[Escher2112]

very interesting... I hadnt thought of that.

It is just the factory Mac Pro Digital output that I'm using...