I bought my M4 Sapphires direct in June. Out of the box they impressed with lifelike vocals, but seemed a bit edgy in the treble and a mite reticent in the bass. After 50 hours, the treble started smoothing and bass got deeper. At 75 hours, they sounded almost perfect, just the slightest bit of edge up-top. Now, at 150 hours, almost every listening session has moments where I'm startled by the realism of what I'm hearing. The speakers have been (and are) powered by a VAC Phi170 IQ tube amp (85watts/ch) and the bass has become both deep, tight, and impactful. Vocals are even better than before, and high frequencies no longer have even a hint of edge. Details have emerged that I didn't hear at the start, and the soundstage has become both broader and deeper. The speaker they replaced, PSB Imagine T3s, were no slouch - they were Stereophile A-rated. The M4 Sapphires trounced them in my room, particularly in the bass (I never could get bass that was both deep and tight with them) and in sound staging. I'm a very happy camper.