Finally is here, Ayre KX-R + MX-R, replaced my Pass XP-20 + X350.5 combo. So I can compare them as a combo, have no chance to cross test them. I try to describe my impression with my limited English.
Ayre combo is more musical, more intimate, sound stage is coherent but not over big and wide, yet in very appropriate dimension. No big difference in day time or night time. Treble is not as bright as Pass, but not in "dark" category at all. Vocal is very attractive, I feel more close to the singer's intention of their interpretation to a song.
Pass combo is very good if you count their price into consideration, 3D & hologram soundstage and sound extension is slightly better than Ayre, May I say it is more "hifi" feel than Ayre, But it is not as coherent and consistent as Ayre, Pass has very good dynamic, but soundstage collapse in daytime if there is too much light into my eyes. But in the dark, Pass can really suck me in as well as Ayre.
I realize that AudiogoNers' opinion are very close to what I heard from two system. To me, I probably can hear Ayre for longer hours without fatigue, in good detail and very balanced way. Pass bring me slightly more "HIFIish" enjoyment when I hear something I have never heard before. But also not over bright or over analytical. Pass combo will still be my recommended system at their price range. Ayre add slight warmth and integrity to the music, but both sound very neutral to me, and very system dependent to the gears and cables you used in your system, any inferior link could be found easily.
Overall, With Ayre combo, I find a new reference system to the sources.