I don't really know how much, if any, it is colored because I haven't compared it to some other "flat" power amp. I just know it doesn't sound band and, in fact, I think it sounds good.
As far as volume, I think it is plenty loud. I run it at about the 5W master setting and have no problem keeping up with a band with a moderate playing drummer. Also, if I remember right, that manual says it is really more like 100W when on certain settings. I play amps with plenty of midrange that cut through, so I think that plays a factor in how much power you need. I think the more you scoop the mids, the more you need.