IMO the technical aspects of playing bass can be perfected by anyone willing to put in enough hours of practice, but really using the instrument to convey emotion is another matter... though it requires technique of course as well. I am a fan of Tony Levin, and when I first bought a copy of Lou Reed's Berlin years back, I was psyched when I saw Levin played bass on a track. Having first becoming a TL fan after seeing Peter Gabriel live, it is somewhat different here. https://www.youtube.com/watch?v=YY_i-R2ldyA His use of space and the weepiness of the fretless is just genius on one of the saddest rock albums ever made. So I am just curious... Can anyone name a truly sad bass line? One that really moves you?