Pass X150 vs Krell FPB 200

Hello,

I am currently looking at vintage balanced solid state amps and have narrowed the choices down to two. Which amp is the better performer, the original Pass Labs X150 (not the .5 or .8), or the Krell FPB200 (not the 200c or later). I currently am driving Klipsch Heresys with a 6v6 PP amp that I restored, so definitely a pretty efficient speaker. I am looking for more speed, transparency, and slam, though without a loss in musicality.

Thanks!