monitor audio bx2 I used can easily get hardened and yamaha a-s500 wont soft it when its a "bright" amplifier, in the price-range the pure sound in music like vocals, life like naturality its really medium milk, But it will performe dynamics, details and exitements, here it shows up pretty rythmical and the seperation is good.
My opinion was really splitted, in movie soundtracks from like The island, Batman begins/the dark knight that id tested critical, it sounds impressive. But in music it sounds rare good much becouse of the harshness/clinical sound. If the yamaha as500 is partnered with softer speakers and placed in a bigger room it will sound better in music.
Compared to my grandmas 70´s JVC that id borrow it yes lacks the dynamic, details, exitements, rythmical, seperation and openess but sounded better in rest areas, vocals sounded much better, it bring more life like softer music and actually really marked a deeper bass, with dynavoice challanger m-65ex loudspeakers the yamaha seemed to fit better, much more bass maybe little better tone balance.
If you want a 2-channel cinema amplifier i would say go for the yamaha s-500 but not so i wouldnt recommend it /Zax