Twister6 posted a review of the Vega single dynamic driver (DD) IEM over on Head-Fi. Not surprising, the bass is great. Delivering bass with small number of balanced armature (BA) drivers appears to be a challenge which is likely why we have seen the rise of DD/BA IEMs over the past couple of years. The DD delivers the bass and lower mids while the BA drivers take care of the mids on up. Twister6 has comparisons of the Vega with various other IEMs. A very nice review.
Unfortunately, the Vega retail for $1,299 with used going for around $700-800. These price ranges open up a number of other IEM solutions.
Pros: BASS, resolving detailed organic sound, unique shell material, premium ALO cable, leather case, accessories.
Cons: the sound is eartip depended, the bass quality could be source dependent.