How about this: What do you think about have a different color for the waveform graphic for WAV or AIF files? Keep the blue color for MP3 and other formats, but use a gold or other differentiating color for WAV and AIF files.
The idea would be to call these out as superior. It's a visual reminder that calls attention to the benefits of PLUS membership.
I always thought it would be good to annotate the waveform. It could be like soundcloud comments at a specific point in time, create a marker to say "this is verse 1", "guitar solo here", "chorus starts here", etc.
I really like this idea too... kind of a subconscious reminder. It would also give a cool visual cue to distinguish track types. The grey color of the wavform placeholder image would be perfect for that lower quality, just because it feels so generic. It's a little thing, but it would serve as a constant reminder, especially when working in mixed groups of "plus" and free members.
That is a fantastic idea if doable. It differentiates the users without branding them or otherwise labeling them as new or temporary. Very subtle yet easily recognizable.
Sure, Raf...color coding the high quality files couldn't hurt. It's subtle but all part of the "branding" of the PLUS membership. I'm also a big advocate of the Soundcloud style commenting feature.