http://www.listening-tests.info/mp3-128-1/results.htmHow to interpret the plots: Each plot is drawn with six codecs on the X axis and the rating given (1.0 to 5.0) on the Y axis. The number of listeners used to compute the means (average ratings) and 95% confidence intervals are given on each plot. The mean rating given to each codec is indicated by the middle point of each vertical line segment and the value is printed next to it. Each vertical line segment represents the 95% confidence interval (using ANOVA analysis) for each codec.
This analysis is identical to the one used in Roberto Amorim's listening tests.
One codec can be said to be better than another with 95% confidence if the bottom of its segment is at or above the top of the competing codec's line segment.
Important note: These plots represent group preferences (for the particular group of people who participated in the test). Individual preferences vary somewhat. The best codec for a person is dependent on his own preferences and the type of music he prefers.
To save you some time, the quality difference between iTunes, Fraunhofer, Helix and LAME are very marginal, with some doing slightly better than others depending on the type of music. If you like synthesizers you may find Helix marginally better, if you like Rock you're probably better with LAME.
Of course the other thing to consider - does Helix work with EAC or C-Dex?