Airplay vs. Home Sharing, is there a technical difference???

Question

I'm attempting to become an audiophile, or at least I can say I really enjoy listening to music. As such, all of my CD's are ripped via Apple lossless into iTunes, and then streamed to my ATV2 before the optical out sends the digital signal to my stereo.
The ATV2 offers me (at least) two methods of listening to my music:
1) Using homesharing - my ATV2 picks up the music when I select "Computers" and choose my homeshared iTunes library, or
2) Using Airtunes - directly from my iMac and select my ATV2 as the destination source.
Interestingly enough, I hear a real difference between the two methods, as method #2 will create a significant distortion in many songs, but method #1 will not, regardless the music format (lossless, 128kbps, 256kbps, etc).
Why would this be? Is there a technical difference between method #1 and #2 above between what iTunes sends and ATV2 receives/decodes?
Help, inquiring minds want to know!
Thanks.

Answer 1

mightyprops wrote:
I'm attempting to become an audiophile, or at least I can say I really enjoy listening to music. As such, all of my CD's are ripped via Apple lossless into iTunes, and then streamed to my ATV2 before the optical out sends the digital signal to my stereo.
The ATV2 offers me (at least) two methods of listening to my music:
1) Using homesharing - my ATV2 picks up the music when I select "Computers" and choose my homeshared iTunes library, or
2) Using Airtunes - directly from my iMac and select my ATV2 as the destination source.
Interestingly enough, I hear a real difference between the two methods, as method #2 will create a significant distortion in many songs, but method #1 will not, regardless the music format (lossless, 128kbps, 256kbps, etc).
Why would this be? Is there a technical difference between method #1 and #2 above between what iTunes sends and ATV2 receives/decodes?
Help, inquiring minds want to know!
Thanks.
If you lower the playback volume control in iTunes on your iMac when it is sending music via AirTunes to your ATV, can you eliminate the distortion?
It may be that the too-high output volume from the iMac is causing "clipping" somewhere in the signal delivery chain because there is too little "headroom" for the digital audio's loudest passages to be rendered properly.
If so, turning down the volume control in iTunes might fix it.
Technically, if you stream the music using Home Sharing, the ATV is receiving and internally decoding the original audio file. Using AirPlay, the file is decoded by iTunes on your iMac, not on the ATV, and a digital audio output signal is generated in iTunes and sent to the ATV. If not enough headroom is present when that happens, the output signal may be clipped in loud passages. This may happen either at the point of being generated by iTunes or at some later point in the signal path.
You may want to try using iVolume
http://www.mani.de/ivolume/
to make sure all your music files play at the same desirable level. This is achieved in part by turning on Sound Check in iTunes (and also on the ATV) after using iVolume on all your music tracks. Before you use iVolume to adjust the volume of your music tracks, you might want to set iVolume's Master Volume level fairly low, so as to give you undistorted AirTunes play even with the iTunes volume slider set to its maximum position.