Krell FPB 400CX vs PASS LABS X-350.5

Ditto Tvad's comments. If you want to stick to solid state you could also consider the class A models from Plinius: SA-50, SA-100 & SA-02.... or Clayton S40 & M100

I agree with Tvad, and tend to lean heavily towards quality vs. quantity when it comes to amps and audio gear in general. The Nines & the Silverbacks are quite efficient, and should match well with the XA-60.5, even with your musical tastes. Would be interested to hear John DeVore's thoughts / preferences between the two amp in question.

Tvad - my bad... at the risk of sounding like a kiss ass, I agree with your last statement