I should also add that I am coming from the Phonak PFE 112 IEMs which are balanced, neutral, warm, etc. And I think I want a departure from this with my next purchase.
I do like the sound of my TF10s (and I will keep them) but they are uncomfortable as heck!
And I want to get away from BA IEMs and try the dynamic side again.
Vocals on the 77 are better than the 50's. Both IEM's are forward sounding. The Nuforce are more laid back, which makes them easy to listen to for hours. The 50's are forward too but they have that mid-range hole in the middle and the 77's are more flat and neutral so the entire presentation is better balanced in a forward way. One thing I am noticing - the 77's have a 13mm driver, which is thicker in your ear than most. I have small ear channels and with the smaller earpads, there is less cushion around the drivers. I probably have to try some other earpads to find one that's more comfortable because I doubt I'd want to keep these in for an entire trans-atlantic flight.