We play a lot of music in our office. A lot! From 9 to 5, 8 days a week (did you see what I did there) we have everything from Big Band Jazz to Garage Rock to obscure Electro playing through our office iPod HiFi and, aside from the occasional "What the hell is that?" emanating from the back of the room, the question of sound quality always seems to rear it's head.

Now, I take my music seriously (as many do) and, as someone who actively seeks out rare and difficult to acquire records, I consider the playback quality of music to be as important as the music itself. Some may consider this to be a form of acute music snobbery but, for me, it is all part of the same package and in my opinion sound quality/production is something which can either improve an average album or destroy a highly regarded 'classic'.

With the transition of music libraries from traditional physical formats to computers and other devices I've always wondered how this affects sound quality. Almost anyone reading this will have made an active decision to compress their music onto their computer at a particular level of compression [generally based on bit-rate and compression codec and/or the capacity of your MP3 player] but how often have you wondered about what effect these changes have upon your listening experience?

As I lay slumped on the sofa one night I decided to put on Radiohead's 'Kid-A' album to try and wake me from my stupor. So I popped open my iTunes library and let it spin. Once the opening 40 seconds of unsettling crowd noise had past the dark silence of the opening track "Everything in it's right place" growled from my speakers. Well, not so much growled as 'pathetically farted in my general direction'. I instantly knew something was amiss and that the bass lines were being clipped somewhere along the line; resulting in a flappy, flatulent noise. Was it the file format, digital output, pre-amp, power amps, speakers or even the power supply? Well that's quite a list of suspects and quite frankly I was too tired to transform the living room into a sound lab and start measuring wave refraction and timing discrepancies caused by speaker placement and/or room acoustics. So I simply popped the original CD into my CD player and let it spin. Voila! The flatulence was gone but the rancid scent of technical mischievousness was still present somewhere.

(Now before we go any further I should probably mention a few salient pieces of information; I have been, for want want of a more complimentary description, an 'audiophile' *cough*splutter*gag* for quite a few years and I've owned considerable amounts of HiFi from entry level Kenwood and Sony separates, to mid level Rotel and NAD all the way up to HiFi heavyweights such as Linn, Wadia, B&W and TaCT. I've also dabbled in parametric equalisation, golden-ratio rooms and music production so I'm pretty well versed in optimising HiFi setups to get the best from them. Now that that is out of the way you'll hopefully think of me as less of an idiot and more of a loser spending too much time fiddling with industrial gauge wiring and ceramic fuses.)

So back to Radiohead and their mighty wind. Where was it coming from?

- Source material? I compress my CD's to .WAV format which should maintain the majority of the CD's original .AIFF files sound quality and frequency range so that was an unconvincing no.
- iTunes? Well, it is a beast of an application these days (I still yearn for a 'vanilla' version just for music.) and there are quite a few equalisation options (not that I use them) so that there was a possibility.  
- The iMac's Digital output? I've always wondered about the quality of the optical outputs on Macs and this seemed, at first, to be the most obvious culprit.
- My HiFi setup? Well, the CD exhibited no issues as embarrassing as the .WAV file through iTunes so again, a likely no.

As the CD playback exhibited none of these farty artefacts (Fartefacts? Artefarts?) I ripped the Radiohead track into iTunes but opted for zero compression and maintained the .AIFF file format. Unfortunately the bass was still warbling and compressed but I was actually rather thankful for this as I really don't want to re-import all my CD's again as .AIFF files.

Next up I streamed the audio through an old Airport Express I had sitting around. This would show if the issues were emanating from the digital output on my iMac but alas the distortion was still there on both the .WAV and .AIFF versions of "Everything in it's right place". Even switching to a different digital input on my digital pre-amp made no difference.

It was at this point I decided to take a step back, enjoy a rum and coke and approach the issue from a different angle.

I returned my set-up to its original state and using iTunes linked into both the .WAV and .AIFF on my external hard drive. I then copied these to my desktop and proceeded to play them directly from the Finder - negating iTunes altogether. The results were more than interesting. Neither the .WAV or .AIFF files exhibited any flatulence when being played direct. The sound quality also appeared to be better overall. After a spot of Googling I discovered that I wasn't the only person to notice this. There really did appear to be a noticeable difference between playing music through iTunes and the Finder. Now this in itself is a little odd as essentially iTunes is a user interface for playing back music/movie files from a database/library. These are the same files as those copied to my desktop and even with all the additional programming/code crammed into iTunes there really shouldn't be a difference. Was iTunes really having such an obvious effect on the sound quality of my music collection? It certainly seemed that way.

Having finally identified iTunes as the culprit I decided to re-check the iTunes preferences and lo-and-behold there was something I should have spotted when I started all of this: "Sound Enhancer" was turned on. DOH! After swiftly rectifying this oversight I set about playing the tracks again (through iTunes) and the offending warbling was gone from both the .WAV and .AIFF files. This was one of those head-butting the walls whilst chanting EUREKA! moments.

Now you're probably thinking "What an idiot!" and you'd be right to but I still wasn't happy. There was, to me, an obvious difference between playing tracks through iTunes and directly from the Finder regardless of the file type and no amount of rooting around on the internet could find me a solid explanation. My own opinion is that it is the playback mechanism encoded into Finder and iTunes. Finder is most likely utilising a Core Audio component for playback (as Logic Pro and GarageBand do) but I'm unsure if iTunes uses this. Most likely iTunes uses a QuickTime component and this brings me back to my comment about wanting a 'vanilla' version of iTunes built purely for audio playback. It wouldn't need to use Quicktime and could plug straight into the Core Audio component(s). This would instantly upgrade everyone's audio quality. Will it happen? Well, iTunes is a beast. A behemoth of code bolted together to accommodate the iTunes Store, video playback, the quirky Coverflow system and iPod synchronisation (which includes photos, calendars etc). I fully expect a completely re-vamped version of iTunes to appear along with OS XI - if not sooner. Is it really needed? Not for the majority of users but an improvement in audio quality would be a good selling point for a company who's income stream is bloated by the sales from the iTunes music store.

So what's the moral of this little tale of audio flatulence and oversight?

Firstly, audio file types and codecs are important* but the nasty, in-built equalisation and sound-level features found in iTunes make your file choice almost redundant. If you're listening to your music a lot and through a decent hifi or dock/speaker system then turn them off!

Secondly, in my opinion, iTunes really does have an effect on sound quality even if all the equalisation settings are turned off. Why this is I can't be certain but I'll certainly be keeping my eyes on the internet in the hope of finding out.

Lastly, drinking rum whilst being lazy can make you do daft things like this.



*When importing music to iTunes go for the largest file size you can accommodate. My advice is that if you're going for MP3 compression then always set it to 320KB, don't use VBR (Variable Bit Rate), and never use 'Joint Stereo'. Both of these settings reduce files size further and affect audio quality.