[edwardsean]

I use an Apogee Duet, which just blows me away. However, this little tip provided by Benchmark Audio makes a significant improvement/ correction. Researching it a bit, I'm still not sure whether it is due to the relative quality of upsampling between CoreAudio and iTunes or that it avoids double resampling. Either way, it makes a real difference. The link to the whole article is below, but I quoted the critical statement of the problem and solution.


Problem: "For iTunes versions later then 7, iTunes must be launched after the sample rate is set in AudioMIDI. Any sample rate changes made in AudioMIDI while iTunes is open will not change the sample rate of iTunes until iTunes is re-launched. Consequently, it will cause CoreAudio to sample-rate convert the audio coming from iTunes. The result of CoreAudio sample-rate conversion is significant distortion."

Solution: "An easy, all-inclusive setup is to set AudioMIDI to 96kHz before launching iTunes and keep AudioMIDI at 96kHz. This will lock iTunes at 96 kHz, which will upsample all sample-rates lower then 96 kHz. Setting the default to 96 kHz would allow playback of high-resolution 96 kHz 24-bit files without any processing, and would utilize the high-quality iTunes 7.X SRC only when playing low resolution 44.1 and 48 kHz files, or the rare 88.2 kHz file."

ITunes-QuickTime for Mac - Setup Guide - Benchmark

 

[Currawong]

I saw a similar article on this linked from another thread, possibly the "Apple lossless isn't lossless" one. I'm considering ultimately getting an Apogee Duet as well, especially as everyone I've heard who used one says that the difference was huge.

 

[Jaska]

I'm hoping some registered owner of a Duet will contact Apogee tech support to get the skinny on the preferred configuration for iTunes 7, just in case their point of view is any different than Benchmark's. I've already submitted a couple of questions to them, and don't want to be added to their "overly inquisitive customer" list.

 

[fault151]

what is apogee duet? I have a mac and itunes plus an external dac, could it improve my sound? What does it do?

 

[Jaska]

Quote:

Originally Posted by fault151 /img/forum/go_quote.gif what is apogee duet? I have a mac and itunes plus an external dac, could it improve my sound? What does it do?

Apogee Duet


Follow the link above for details on the product. Also, you could use the Search function here to read plenty about it.

 

[IceClass]

Quote:

Originally Posted by Jaska /img/forum/go_quote.gif Also, you could use the Search function here to read plenty about it.

Erm...dude; the search function has been nuked for a while now.

 

[Joelc87]

Audio MIDI setup won't let me turn my HeadRoom Micro DAC any higher than 16/48. It should be able to go to 24/96.

 

[TR909]

Ditto for my Pico...

 

[Jaska]

Quote:

Originally Posted by IceClass /img/forum/go_quote.gif Erm...dude; the search function has been nuked for a while now.

It works for me, granted I usually end up using the advanced search function to search by thread titles.

 

[koto-in]

Quote:

Originally Posted by Joelc87 /img/forum/go_quote.gif Audio MIDI setup won't let me turn my HeadRoom Micro DAC any higher than 16/48. It should be able to go to 24/96.

USB Audio is limited to 16/48. If you want iTunes to upsample your audio, you have to use the optical output.

 

[koto-in]

Quote:

Originally Posted by TR909 /img/forum/go_quote.gif Ditto for my Pico...

USB Audio is limited to 16/48. The Pico is upsampling the audio signal to 24/96.

 

[TR909]

Gotcha, forgot about the USB limitation, I'd been using optical out until the pico. So..in that case, should I set AudioMidi to 48 or 44.1?

 

[Jaska]

Quote:

Originally Posted by TR909 /img/forum/go_quote.gif I'd been using optical out until the pico.

In that case, it isn't a digital signal going to the Pico. It will be treated as analog coming through a mini TRS connector.

 

[grawk]

With the pico, I'd suggest setting it to 44/16. After all, most of your music is going to be sourced from cd anyway. Leave the upsampling to the pico.

 

[Jaska]

Quote:

Originally Posted by grawk /img/forum/go_quote.gif Leave the upsampling to the pico.

x2