answer:There’s definitely an audible difference between 128 and 256 if you’re using good equipment. In my experience, the difference is not noticeable in everyday use for most tracks. But I keep my iTunes sampling set at 256 because I think there is an intangible difference. For example, I can’t always hear the difference between different headphones, but over time I can tell that certain headphones make my ears fatigued. Since you have the space, go for the higher quality.