I have had mine for a year and find it very transparent. It lets the character of one's preamp shine through. I have the AR LS-27 preamp (tube) which mates nicely with the 450. They drive my Wilson Sophias sublimely.
Looking at the Audio Research DS450 - once again
.....I am once again at a position to seriously think about this amp. I have no access to litening to it ....and based on dealers, and reviews...it seems like an all around winner. Yet as much as they work around it,...it is a class D amp. Maybe ARC has developed one that does actually sound good. I would like to hear from members who have listened to it, bought it....or said no to it. Please, if you haven't done any any of these no need to respond