Since Innerfidelity apparently made the Logitech 6000 their favorite closed headphone in Passive mode, I did a direct comparison to the v-moda M80. The M80 absolutely kills the 6000 in Passive mode. The M80 has a soft treble and the 6000 sounds like a blanket is over the speakers. The M80 has a neutral bass with a strong bottom end, and the 6000 is boomy beyond belief.