When I played the Legacy, I noticed right away that the clean channel was decent but that the gain channel was very dark sounding. I was surprised to notice that it was even darker than my triaxis preamp.
The line 6 amps are for guys who wnat to plug and play and don't care about tone. IF you don't mind the compressed tone and lack of dynamics,then a line 6 amp might be good for you.
Digital may improve to the point where it replaces tube circuitry, but that wont be for a long time. So for me, Digital isn't even a consideration as a main amp.I do have a pod for practicing, and late night direct recording.
But as said above, getting the legacy combo is way better for you than getting the head.If oyu get the combo, oyu can always buy a second
speaker cab and use it along with the head
Never try to power a stereo with an amp, you will not only fry your stereo but most likely ruin your amp as well.IT is possible to use the preamp out of most amps and make it work with a stereo that has a line input but otherthan that, don't do it