You only need to add amplification if your current AVR does not go loud enough. External amplification won't sound any different.
From all reports XT32 is pretty great and a lot of people like the higher end versions of YPAO, 20 and 30 series (eg, 2020, 3030 etc..)
So if you like how it sounds now and it goes loud enough and has the features you need then you won't gain much by changing to another AVR.
Klipsch RF-62II, RC-500, RS-400, SVS PC12+,
Def Tech SC8000
Harman Kardon AVR 1600
PS3, Apple TV, Sharp 70" Qattron