itunes...do all versions sound the same???

I just got an iphone and I plugged it into my mac mini and it told me that I have to download the latest version for it to sync. I have been using itunes 7.4.2 for some time now and have zero complaints. I have a huge itunes library and so far no problems, hence my reasoning behind not updating. The features of the newer versions have not been enough to sway me to update.

I read somewhere that the newer versions of itunes don't sound as good.

Is there any truth to this and is there anything to fear in updating my itunes to the newest version 8?

I'd like to sync up my iphone but I don't want to lose a bit of sound quality in the process. I'd rather not link it up to my itunes libraray if that is the case.