Tpk123, it's been a few years already since I last compared a Krell vs a Pass Labs X-series amp, but even than, for my ears I found the Pass Labs to be a more musical/natural sounding piece. It had all the dynamics/slam of the Krell plus the above stated virtues. However, the new Pass Labs X-.5 series amps are not just slight improvements over the first X-series but a shift towards the sound of real music. They have much of the warmth/sweetness of the XA-series amps but the dynamics and power of the X-series. So to be fair I have not heard the latest generation Krell amps, but unless they have dramatically improved, my hunch would be the Pass Labs X-.5 series would still be the better sounding amps. I replaced a great sounding amp[Edge NL-10] with a Pass Labs X-350.5 because it just sounded more real and musical in my system. However, as you know personnal taste and system synergy always comes into play, so a home audtion using your ears is always necessary. Hope this helps.