I'll second Mapman's comment. The SB3/Classic and Duet models were fairly good mid-fi in terms of sound quality. They improved substantially with the use of an external DAC.
The Touch is significantly better by itself. I know some still prefer an external DAC, but as noted, I ran a side-by-side, synced and level-matched comparison between the Touch and a Lavry DAC for several weeks. I routinely found myself unable to tell which was playing unless I checked the position of the input selector on the amp.
Now, that may be due to my pedestrian system, aging ears or utter lack of audiophile sophistication, but I'm enjoying my music.
With a relatively low up-front cost and the money-back guarantee, it strikes me as a pretty easy decision to find out for one's self.