SD is pretty messy with lots of noise and ugly stuff, and HD cable even is quite variable in quality. Some channels will look great (though with some noise if you look for it) and others are still quite fuzzy.Isn't it interesting how this mirrors audiophile systems insofar as faults of the source become more apparent as the playback system becomes more resolving?
It's a primary reason why I have not made the change from my standard def Sony XBR CRT.

