I re-calibrated and lost absolutely nothing in sound quality. I've listened to a few more tunes and without a doubt, the M5 resolves better across the entire frequency range. The M5 sounds more natural and you don't have to strain to hear how more natural it is. However, there does not appear to be a difference in the eerily holographic quality of the soundstage - both are the same in that regard. In fact, as I reported above, the M3v4 disappears better. I have to spend more time to understand if this is the way the M3s are positioned relative to the M5s - the M5 tweeter is at ear height while the M3 tweeter is 5" below.