There definitely is a significant difference when comparing the SoundMAGIC PL50 or Klipsch S2 with the top of the range In Ear Monitor (IEM) earphones like the Westone UM3X.
Saying that, the PL50's are good value for money and the overall sound quality compares well with many earphones costing more. Bass response is on the lighter end of the scale, but they have LOADS of clarity and detail. Check out this
review of the SoundMAGIC PL50 by Stuff Magazine.
The Klipsch S2 has a bigger bass response than the PL50, but does not have the accuracy of the PL50. The Phonak PFE 012 offers all the clarity of the PL50, better bass response and higher end build quality.