One thing I'd have to disagree with in this thread is the amount the burn-in that changes the FX-850. Let me clarify for those who've yet to pull the trigger on buying these. They have quite a bit of bass heft that does seep into the lower midrange and it can definitely make 'apparent' detail blur up, but that's just how 100 - 500 hertz is when boosted, not because the headphone is muddy. Those who claim it has slow, unrefined bass at first are wrong, it's just the apparent detail isn't clear, and after listening to these for a month I've realized it's very possible to adjust and get past this 'muddy' sound, but it's not because of burn-in, it's mental adjustment. Going to a different headphone and back makes me realize this everytime. Also, these sound fine off a lowly source such as the sansa clip+, but they definitely scale up with my modi + magni in an amazing way. --- and a last note, the cable is extremely prone to coiling from normal usage, it twists up and likes to stay twisted. Not sure if it's a norm for IEMs, but my XB90EX doesn't do that so I thought it's worth noting.