Ok, so these are not the bees knees for IEMs. From what I hear, they seem to have a slight inverted V shaped frequency response curve. They sound great with vocals, with luscious mids. To be fair, so far, I have only used them directly with my phone, without any external amp or DAC. Perhaps when paired with external DAC/amp, they will sound even better.
However, for the price, I think they are amongst the the best valued IEMs in the market currently. I could certainly live with them when I travel and do not want to carry bulky headphones with me. I would highly recommend the Hippo ProOnes to any one who is looking for a highly portable solution to their music listening via mobile devices.
-Jaben Luvs You