Unfortunate news on your motherboard/audio distortion. I only hope it is a rare phenomenon.
I have found Apple UK to be better, but Apple support has never been great, I have paid for Applecare which I hope I never have to use. This is 24hr at site hardware replacement and 24/7 'phone hardware/software support at, I think, 129GBP for two years beyond initial. Primary reason is hardware, a G5 Quadcore, 8Gb ram and two 500Gb drives as RAID 0 stripe. Plus an iBook.
In the 12 years I have been using Macs I have had a MotherBoard failure on an iBook, most of that particular model failed, then failed again after m/b replacement. Of the scores of Macs with which I have been acquainted, I also run a Mac hard/software support group in my 'free' time, I know of three m/b fails[see above] and one ram[not vouchsafed] failure.
There is no perfect OS/software/hardware yo pays yo money yo takes yo choice.
People screw up, systems become confused. Do housekeeping.
With a glass of Sauvignon Blanc and shavings of Mimolette, I bid you goodnight. M.