i have found the david belles amps to be slightly on the bright side of neutral (this is true even for his wonderful sa30 class a unit, which i have kept), a consistent trait/voicing of his products relative to other serious solid state amps such as ayre, pass, hegel, gryphon, boulder
the aria in particular has a certain fine grain and sizzle to the treble... which can be a boon for certain types of speakers with laid back tweeters that overly smooth out the sound