I've run the AFXIII through a few different tube power amps/FX returns. I prefer using it with a solid state PA power amp (I use a Crest CA9). Something about the tube power amps made things a bit "cloudy" or soft compared to the Crest.
But not all power amps are the same, of course, and we have different tastes.
But not all power amps are the same, of course, and we have different tastes.