Pass XA 30.5 with Revel F 208 ?

It might sound good but will be way underpowered. 20 watts of warm beautiful power only goes so far with speakers that are happy with 400 watts. Keep your choice above 90db for that amp (B&W, Coincident and many more)

The XA30.5 puts out a lot more than 20 watts after it leaves Class A, so a lot depends on room, volume levels, and whether you want/need to stay in Class A

The XA30.5 is underpowered for the Revel F208 or F206 unless you like to listen at really low volumes. Yes, the XA30.5 will put out more power after it leaves class A, but it's unlikely to really go above 60 wpc. Revels are not the easiest speakers to drive and as Elevick points out, Revels can be quite content with 400 wpc. I drive a pair of Revels with a Pass amp that puts out 300 wpc into 4 ohms, and even then in my moderately sized living room, I think the tank is a little light on the octane.