Pass labs xa30.8 vs Krell evo 402e

Yuhengdu, perhaps your speaker placement and room interaction is not optimal? Pass and C1 pairs favorably for me. The Krell might give you more resolution as Extravaganza mentioned. You have to bring in the krell or other amps/sources to experience which one sounds better. Enjoy the search.

Sort of like comparing a boulevard cruiser to a muscle car?
I can't say from experience, but it appears as though your speakers are bit insensitive. As such the more powerful Krell (yes, I know the xa30.8 has much more headroom than might appear at first glance) might help with your immediate concern, but what other trade offs that come to be, might or might not be worth it. As suggested above, there might be other ways to remedy your concerns.

Thank you guys, these are all very helpful. I will try to do the audition myself and I think that helps the most. You are right @Unsound I think the speakers are bit insensitive.

Also, someone is selling a cello duet 350 on audiogon. How would this amp compared to those two mentioned in this thread then? I know they use their own type of plug and I wanna know the resale value of cello too. Thanks!

Dyn C1 requires more power. The X250.5 was an excellent match.