i used to use thiel 3.5's in my main system, & they weren't too bright, even when my adcom gfa-555 was the main amp, & not relegated to subwoofer duty! now, the thiels are doin' yust fine, in the kitchen, powered by a 35wpc audio-innovations integrated, fed from the main system thru its tape outs. hook up a turntable, & then see if the fatigue goes away. or, if ewe have a quality tuner, & uncompressed radio station, is there fatigue here, too? i'd suspect the fatigue is coming from your cd-player. when i had a solid-state preamp, the only way i could get rid of cd-fatigue was by using an ase z-man tubed buffer-stage, even w/speakers other than thiels. now, w/a tubed preamp, i don't need the buffer-stage.