10.9.2 audio

Dear collegues. I am a professional musician and electronic music teacher. I had for about one year a plaguing problem with my iMac 27" late 2009 quad-core i7.

It has been discussed many times over the net as an "audio stutter" and "CPU Spike" problem and was very often linked to my iMac model:

Basically after some hours or minutes of use and more often after a sleep recover, my CPU was spiking during audio playback in DAW software (Mostly Pro Tools 11, but also Cubase and other platform) and the audio was stuttering and distorted, often resulting in playback stop with Buffer errors.

The problem was already present in 10.8 but was not present in 10.6. I thought that the OS upgrade could just be a coincidence and that it could be a hardware problem. The Apple Hardware Test found no problem in hardware but the malfunctioning was constant.

I remember in the update list for 10.8.4 and 10.8.5 already mentioned a generic "Audio problem" correction, but the situation remained the same. Also the internet forum were full of people complaining about the problem still remaining.

I was about to sell my iMac for a Windows computer then i noticed the 10.9.2 upgrade yesterday morning. BAM! The problem is over. I had renounced to my iMac as audio computer for 6-8 months cause it was impossible to work with audio (i just used for internet and generic use) and now happily my computer is working perfectly as it did with 10.6.8.

NOW WHAT I WANT TO KONW POSSIBLY is: What was exactly the problem?

In the update list there is just a generic :

Fixes an issue that may cause audio distortion on certain Macs "

I think WE HAVE THE RIGHT OF A COMPLETE KNOWLEDGE of what is causing problem to our system, as it is for a small professional a matter also of budget and critical reliability. I am also a teacher so i find very ethical to be able to explain to my students where the problems come from and not just tell them "let's hope that Apple will find a fix sooner next time....". I believe it's a matter of user responsibility and of professional relationship between Apple and its customers to have the possibility to access a detailed technical description of bugs. I hope there's no intellectual property problems into this open and responsible customer care.

SO Basically, anybody knows how i can get some technical information on what the audio problem that plagued the iMac systems for over an year was?
Thanks for the help!

Alessandro