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iTunes: dynamics, midrange gone 'til restarted

Has anyone else experienced this? Upon occasion,when I have shut down my Mac Mini, then restart, and restart my iTunes, I sometimes get playback where the dynamics are gone, and the mid range is non-existent by comparison to it's normal function. This is not a subtle change in sound, it's very pronounced.
So far my successful work around has been to simply restart the iTunes, and the problem resolves.......until I shut down my computer again. I'm not absolutely sure it happens with every shut down, but it may.
This caused a pronounced freak out after taking my system down, installing my new DACMagic, and not figuring out for awhile that my sound problem was the iTunes, rather than the much anticipated DACMagic!
Anyway, anyone else? And is there a way to make this problem go away?
rabco
rabco OP
49 posts
 
Elf73, I have my Mini "hardwired" to the DAC with a USB cable, probably as you deduced. I wonder if reconnecting the Airport changes a setting or such in the iTunes program? If I restart the iTunes, everything is ok.
I probably should report this to Apple. I just wanted to make sure I wasn't the only one with the problem.
It'll give you a heart attack if you don't remember it in association with the installation of new hardware!
elf73
104 posts
 
Yeah it is very disconcerting...

I have checked and my settings haven't changed. And for me, with streaming to the AEx, I don't think the AudioMidi settings even factor in.

For you since you have it hardwired, it may be a different story.

I have mine connected to from the AEx into a DAC through a toslink cable.

I'm almost positive, from your description, we're encountering the same problem. The sound completely recesses at some point.

Once you re-start itunes, does it remain stable. That is, the sound stays to your liking?

I've read something Benchmark put out about the sampling being done either through itunes or the operating system, something to do with "coreaudio", or SRC (Sample Rate Conversion), "truncated word-length". I didn't fully understand it at the time (I'll blame it on jet-lag)...

I couldn't find the article, but here is one that may help. At least, it'll help with your AudioMidi setup:

http://extra.benchmarkmedia.com/wiki/index.php/ITunes-QuickTime_for_Mac_-_Setup_Guide

Found it:

http://www.benchmarkmedia.com/feedback/issues/122007.php

I'll re-read it, and if you can make sense of it in practical terms.. let me know.
rabco OP
49 posts
 
Not sure how practical it's been, but it's interesting reading.
My experience so far has been this: The MIDI Pref window will allow me to set the Properties for the Builtin (Audio) Output to 96hz 2-channel-24 bit (my rig is a 2 channel setup).
But when I try to configure the Properties for the Audio Output for the DACMagic (C-Media USB Headphones), the window is only allowing a sample rate of 48hz (or 44.1) 2-channel-16bit. 96hz 2-channel-24 bit is not offered as a choice.

The DACMagic hardware is only showing an incoming sample rate of 48hz, supplied via USB cable.

So far I haven't managed to trigger any bad behavior while manipulating these settings....I'm just a little puzzled why I'm not seeing a higher sampling rate. Is the sampling device dependent, file dependent, both?

Wondering if I've buggered the settings somehow....
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