wayne

Yes jitter has always been a controversial subject. But this is what I read on a study. In Computer Audio systems, a clock that is software generated from an even higher frequency CPU clock. In the case of the master clock being software generated, the jitter can also be dependent on the program code. So program code does affect the accuracy of the clock and thus jitter?

Just realized I was really late to this discussion. I am using A+ 2.0 without iTune. Boulderskies: I encourage you to trial A+2.0 without itune. Just set it to iTune's library.xml. It doesn't copy the files, just referenced. Let me share my setting in A+ and also related things: - Bypass Apple's core audio use izetope option in A+ (I think this is the reason why A+ sounds better then iTune) - Enable all options under system optimization tab set priority to A+ to Extreme - Use integer mode - I upsample everything to 196 - You can EQ with A+ also - I don't use USB, too much noise. Maybe it's the USB that has too much noise that nulls the difference between players. I use Weiss Int 204 USB/SPDIF converter with linear power supply to feed my DAC). USB will transmit all computer signal (in power supply) noise down the path! I think USB port on computer and a lot of DACs are the weakest link. Many of the DAC has separate power supply. - I also ensured that I have no switching power supply anywere in my audio chain. Switching power supply has a lot of noise. My mac mini is modded with linear power supply DC-216 from KECES, even my Weiss Int204 is fed by a linear power supply that's twice the size. - I disabled wifi and connect my computer to router. Wifi and bluetooth generate extra work load and thus extra signal noise within computer. I too didn't believe why 2 bit perfect program can sound different. I also didn't believe using A+ without iTune at all can make a difference. But I trust me ear. I think there are many reasons for this. One being Apple's core audio sucks but then there are way too many factor to consider. I live in Hong Kong but I welcome anyone in Hong Kong to listen to my system.

There is a huge difference!! I think there are maybe 2 reasons, as we age, our hearing gets worst. For people over 35, it's hard to hear above, I think it's 15khz. It gets worst as we get older. The second reason might be your audio system/room acoustic is not very resolving. If you listen on your laptop speaker or computer speaker, you can't really tell the difference

I too have a highly resolving system comprise of Burmester B80 speaker, 088 pre and 911 amp. I can tell the difference between apple lossless and AIFF! Apple lossless sounds thin even with A+!!! I think it's due to computer noise (in signal) and jitter. Computer generates a lot of signal noise. When there is an extra computing step of decoding ALAC to AIFF, there will be more signal noise and jitter. That's why there are many OSX Optimisations scripts and suggested iTune settings for optimal playback. They are all aimed to cut down extra signal noise coming from unneeded computing processing. This is why I modded my Mac Mini with a linear power supply. The original switching power supply generates a lot of signal noise! Now preferably, a computer used as a music server should be fanless because fans also generate signal noise. There is a power filter for fans, but it doesn't fit in a mac mini. If you don't believe how even a tiny bit of signal noise can sound different in a high resolving audio system, I suggest you to play the same file on your computer and on Aurender X100, S10 or W20. They are essentially audiophile grade computers that cuts signal noise. (either from hardware or software). The W20 goes all out with battery for playback and analog stage output, evan has a input for exteral world clock to cut down jitter.