Blah, i had written a nice long response but my browser crashed (&$#( Flash).
Anyway, short version: A151 nice buy at $50. Isolation disapointing(vented housing, hence siren, foam/tri-flange tips won't fix it), stock tips suck(go hybrids), tuning unique, worse then other single armatures in detail(i.e. similarly priced at MSRP er6i), ljokerl's review is spot on: warmth and noticeable grain in highs with lack of sparkle*sparkle. Splits difference between strengths/weakness of dynamic/armature in price range. Build quality decent, cable is unobtrusive/awesome, shiny chrome painted parts look cheap in person and I feel will chip off eventually.
I'm happy with mine after 4-5 months.