Another thing to consider if using Entymotics and StarComm.. The Er6i's have a lower impedance value than what the StarComm differential amplifier is happy with. This can cause the StarComm's power amps to reach thermal overload on hot ambient days (>90F) resulting in severe distortion.
The ER6's have a much higher impedance value than the ER6i's, and is slightly higher than the stock StarComm ear buds; they work perfect, even on blistering hot days and sound much better than the stock StarComm earbuds.
Additionally, the ER6's actually have a better frequency response and better bass than the ER6i's. The ER6i's, according to a tech rep I spoke with, were designed for use with low output devices e.g. plugging directly into a cd player, mp3, etc. Most of us are running some type of amplified system, be it StarComm, AutoCom, or Boostaroo so it doesn't matter. My .02 and 150 hours worth of trouble...