I would agree that 128K files can lack a lot of detail with certain genres however I seriously doubt whether the difference is "unmistakable" at 320K. If this is the case then I suspect your PC audio system is the cause. The empeg sounds an order of magnitude better than most PC systems.

I haven't heard of anyone consistantly identifying an MP3 track at 256K/sec in a controlled blind test against the CD original. A number of tests have yielded similar results at lower bitrates but I suspect that these are very genre specific.

In practice the majority of our clients report that 128K is satisfactory for them and a significant minority (myself included) encode at 160K. My experience has been that whenever I note a track with poor quality, I later discover that the original CD was dirty or worn. In other words, ripping was the problem, not encoding.

Rob