iTunes 8.0.1 bad quality MP3 file playback

I've run into the same problem with mp3 files played on iTunes and on my iPod classic. There is a lot of distortion during the loudest parts of the music -- kind of like the sound you get when overdriving a cheap pair of speakers. Some of the mp3 files were from Amazon.com, and some were free (legal) downloads from hearitfirst.com.

@Mystic -
I'm posting same info here as on another forum where I saw your post - hoping to get some info/awareness from others...

I'm having same 'upgrading to iTunes 8.0 has made my iTunes library sound like poorly compressed 40 kbps net-radio crap' (approximately). Thought at first my speakers were blown but experienced same on headphones; tested that it's not my Mac's sound-card by playing an .MP3 in-browser which sounded normal.

Any music through iTunes since 8.0 upgrade sounds awful: trebles are virtually absent, low end frequencies are muddy; mid-range is relatively untouched; all my tunes sound like they were ripped at 40 kbps and "compression-sound" is overwhelming. It's occurring w/ the gamut of sound files in my iTunes library: .MP3's (constant and variable bit rates from 128 - 320 kbps), AAC's ripped from CD's (160 - 300'ish kbps) and purchased AAC's from iTunes store. Multiple combinations of disabling and re-enabling Sound Enhancer and Sound Check in iTunes as well as disabling / re-enabling the EQ (Window > Equalizer) have not resolved.

Everything coming through my iPod Touch sounds perfect as usual as well as music played outside iTunes i.e. games and music through Safari or FireFox.

I updated both iTunes and Quicktime within past week through Software Update, so not sure yet if it's caused by one or the other. For street cred., I'm a long-time musician and work in i.t. system ops. / Mac freak, so while certainly not infallible I'm going to edge past this being user error on my part. A thousand blessings on anyone w/ some thoughts, tips...cheers.

Found some temporary resolution but by no means permanent fix as it has reduced my audio to one channel:
I ran Audio MIDI Setup
(/Applications/Utilities/Audio MIDI Setup.app)
and opened 'Properties For: Built-in Output' ;
under Audio Output I've got format 44100.0 Hz, 2ch-24bit showing as I imagine most do by default on their Mac's;
killing either of the two channels showing (by clicking Mute on either channel) completely resolves; tinny-treble sound disappears, bass is back, muffled sound and compression artifacts disappear; however I'm only getting one channel through my speakers or headphones so this isn't a permanent fix. Oddly, I just realized the 'volume up/down' sound effect on my Mac that happen when adjusting volume via keyboard had been missing until I muted one of the channels via MIDI setup; now my iTunes sounds normal and sound effects are back but I'm hearing only one channel (grr).

I've been having the exact same problems as this! At first I thought that I had blown out my other speaker (one was already damaged, rattled every once in a while, took it apart and now it doesn't work at all b/c I broke the wire 😟 )and got really ****** but then I played music in Windows Media Player, and it sounded fine, so I know its not the speakers or sound card. I hadn't even done an install or anything since last using it normally!

I have since uninstalled and reinstalled the newest version off of the Apple website, no remedy as this( http://www.hydrogenaudio.org/forums/index.php?showtopic=67424)website said.

Haven't found anything for a remedy of a problem-will post here if I do. Hope somebody does because this is ******* me off, I usually don't have a problem with apple stuff, other than iTunes is slow, but this is ridiculous!

Oh and I have my whole music collection in 256 bit unprotected MP3s.

Message was edited by: Durkle

If you delete the iTunes preferences file and restart iTunes it works for a short while (until it manages to write somethign wrong in the preferences file again).
Whatever is causing this is a preference somewhere....or whatever can be repaired and ruined based entirely on a preference file.

on a more positive note, this doesn't really seem to affect people with the laptop speakers or Bose speakers....the absence of highs, and the muddled, unintelligible lows just make it sound like a normal fidelity song being played on a Bose speaker setup :-D (no highs, no lows, must be Bose)

are there any settings that could affect the actual audio signal that's sent thru the optical connection on the MBPs? it sounds like 8bit 9600khz...or worse...i have the output set to 96khz 24bit and that's all my preamp tells me about the stream

all of my music is license free apple lossless...all 1.04TB of it :-D...so, i can't keep deleting that plist file and having it determine all the song info and "gapless playback" info every time i load this program...it takes FOOORRRREEEVVVEEERRRR


<Edited by Moderator>

Thanks for your post. I have the same problem. Where do I find the iTunes preferences file?

I can say "me too" for the distortion problems. I can prove the distrortion is not from speakers, levels, encoders or sound cards.
I copied a non-iTunes-sourced mp3 onto my desktop. I then imported it into iTunes. When I played it back using iTunes I heard distortion. When I played the same mp3 from the desktop using Finder's "Quick Look", the distortion was gone. I imported the mp3 into Logic Studio and there was no distortion there either.
I am using a pair of powered JBL near field studio monitors driven by an optical digital stream from a Yamaha firewire digital audio workstation.
Apple needs to fix this one soon or I will be looking for an iTunes replacement.

I did a little more testing and got interesting results.
I placed a non-iTunes-sourced mp3 onto my desktop and imported it into iTunes (8.0.2). Then I imported two versions of the tune into Apple's Logic Studio; one from my iTunes Library and the other from the desktop.
Neither version is distorted when played from Logic Studio. This tells me that the files are fine; iTunes introduces the distortion in playing them back.
Maybe iTunes 8 has not damaged all the mp3s I have loaded into it since 8.0 was released.

I too am having the weird muffled audio problem: Itunes 8.0.2 on a stock Macbook Pro going to high quality Sennheiser headphones. Mac OS 10.5. It sounds like the vocals are coming from a distant room, all muffled and out of phase. It happens on all my music, with various sample rates and such, these files used to play just fine. Applying the turn-off-a-channel fix cures the sound but leaves me with mono in both channels (shouldn't it kill the signal to one channel?).

He guys any luck on this ? I have the exact same issue ... plays great through quicklook though !...