I have been using iTunes AAC 192 kbps (and LAME 3.96.1 -v2) for some time now and am very happy with the sound. I primarily listen on an iPod with Apple buds (exercise), Sennheiser PX100 (walking and travel) or Bose Tri-Ports (home or office). I am about to upgrade my equipment to some higher end headphones to replace the Tri-Ports and was wondering if anyone with golden ears was experiencing artifacts with AAC 192?

With my ears and my equipment, AAC 192 is transparent but the equipment is about to change......

Does anyone use AAC 224 or 256 and have they found it much improved over 192?

I know most say AAC 128 is sufficient for them. i can ABX 128 files however.

I did some abx tests with itunes aac and a pair of Sennheiser 580 headphones. I could abx a lot of classic samples at 128, I did not so great at 160, and I utterly failed at 192. based on that, I could not see a reason to even bother with 224 or 256. Of course, my 46 year old ears maybe the problem

In the tests I've done on my own, the songs I tested I could generally ABX until up to 224 kbps. 192 kbps was barely ABXable to me but once 224 kbps was reached it was impossible for me to ABX. Though I have found that when just listening for enjoyment, 128 kbps artifacts do not bother me or are not noticable to me so I decided to use that.

I think you are pretty safe using 192 kbps for your encodes because (in my opinion) unless you are listening extra carefully I doubt you will notice many artifacts in your music.

Yes, I cannot ABX any - but you were able to up to 224? That is why I seek the advice of others. Thanks. I wish iTunes music store offered 192 or 224 downloads like BuyMusic.com does with WMA 256 kbps downloads.

Some people can probably ABX AAC @ 448Kb/s or Musepack --quality 10. IMHO that has nothing to do with the settings the rest of us should use.

The version of the encoder that is used also have a lot to say. The latest (qt 6.5.2/itunes 4.7) is a lot more tweaked than the first revs.

Awhile back I did some blind ABing (not ABX) with Grado SR225s and a Meta42 amp with an Audiophile USB and perferred the 224 kbps quite a bit more than 192. Which was closer to the original? Suspect the former, but who knows? Certainly there was a difference.

Have since moved to Ety ER4S & Senn HD650 and an Emmeline SR71 and would like to do some detailed tests, but haven't. Did some quick trys on an iPod between ALAC, 320 and 256 and at least with that source couldn't tell the difference.

Disclosure: I really doubt I have Golden Ears*, so suspect finds of those that do to be more dramatic.


* Never did, but being a gunnersmate in the Navy finished off whatever was there.

I cannot recall, what file size limit forces the iPod to directly access the hard drive, draining the battery quicker? I think I read 10 MB somewhere. That is, of course, another consideration. Any song over 5 minutes enters this territory at 224 or 256. I listen to many songs that clock in at 5 to 7 minutes. If it is 15 MB or higher though, I think I may use 256 kbps based on the commentary here. I need not concern myself with space on my 250GB iMac and I can be happy with 500 songs on my iPod Mini and 2500 songs on my iPod. It would only be the battery I am worried about. It sucks enough already at MP3 LAME 3.96.1 APS and AAC 128 and 192.

I think this limit is gone with the 4g ipods. When playing a wav file on my ipod it has
to spin up a lot more oftern than with AAC or MP3 but its looks like it is still caching
the files it 40 mb (Note I was just testing to see if it could play waves I could be wrong
about what I have just said)

The length of the song shouldn't matter too much for HD access. If your listening to many short songs in a row the player will have to access the HD just as much as it would for one long song (provided that the songs are the same bitrate). However bitrate does matter 256 will always take more battery power than 224, which will take more power than 192 which will take more than 160, etc. AFAIK there isn't any "magic filesize" like 10mb which would drastically affect battery life, nor does it make any sense to me. If battery life matters to you as well as quality you should probably factor that into your decision as well.

Apple claims the magic number of 9Mb, which using average song lengths of pop/rock/rap/etc. would be around 224 kbps.

I thought I saw that somewhere. Yes 224 would be about the max file size for an average song before exceeding this.

don't use AAC then! It needs much more power over mp3!

http://www.hydrogenaudio.org/forums/index....ndpost&p=247869
http://www.hydrogenaudio.org/forums/index....47&#entry257947
http://www.hydrogenaudio.org/forums/index....ndpost&p=257958
http://www.hydrogenaudio.org/forums/index....ndpost&p=252692
http://www.hydrogenaudio.org/forums/index....ndpost&p=253100
http://www.hydrogenaudio.org/forums/index....ndpost&p=253160
http://www.hydrogenaudio.org/forums/index....ndpost&p=252712
http://www.hydrogenaudio.org/forums/index....40&#entry258040
for more use the search-engine....

also, as you can read in some of these topics...I've tested it myself on an iPod mini. Also, put an empty file called _show_speed in your device folder of your iPod and it will show you the current CPU speed...in order to make it to work you need to have the time in titles on...