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Comment by AngryParsley | Hacker News Reader

If you're on a mac, you can obviate a lot of bit depth issues by opening /Applications/Utilities/Audio MIDI Setup.app. From there you can see all your audio input and output devices, and set their frequency and bit-rates. Most default to 44kHz/16-bit, but a saner setting is 44kHz/24-bit.

You can see the objective differences between 16-bit and 24-bit output in NwAvGuy's measurements of the 2011 MacBook Air's DAC: http://nwavguy.blogspot.com/2011/12/apple-macbook-air-5g.htm...

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I may be wrong but as far as I know setting the output to 24 bit only makes sense if your music actually is in 24 Bit. Whatever you set in the Audio/Midi configuration is used as system-wide default output signal - including iTunes and so on. Of course you want to avoid any further conversion in your signal chain, which is why it is recommended to match the output configuration in Audio/Midi settings with the bit depth and sample rate of your music library, which most likely will be 44,1 KHz/16 Bit - unless, of course, you got your hands on higher quality masters.

Considering your advice of setting the output to 24 Bit while your audio collection is (most likely) encoded in 16 Bit, should trigger a conversion while outputting the audio signal - this conversion is useless, of course, as you can't turn this material into something it isn't (imagine upscaling 720p video to 1080p, new packaging, same old content/quality). Yet, and correct me if I'm wrong, the conversion still happens and alters the signal.

So, to avoid this match those audio/midi settings with your music library. There are also expensive iTunes alternatives that deal with this problem by adjusting the output settings to the currently playing audio file on the fly - in case your library consists of mixed bit depth/sample rates. I don't use those solutions though.

Upscaling from 720p to 1080p will not lose any information if it's done properly. Similarly, upscaling from 16-bit to 24-bit will not either, and running the audio output at 24-bit has the advantage that quantization noise from volume scaling is a non issue. This means software volume controls will not result in perceptual quality loss.

I am correcting you: Playing 16-bit audio with a 24-bit output device doesn't distort anything. No matter the bit depth of the audio file you're playing, CoreAudio converts it to 32-bit floating-point PCM. Then it converts down to something the output device can handle. I'm pretty sure Windows does this as well.

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