Would an external DAC improve the sound of my SONY

Since the Sony SACD units are widely modded at reasonable cost this may yeild better value sonic upgrade for less money. SACD Mods has nice upgrade package for $328:

http://www.sacdmods.com/

External Dac would also help but I think you get more bang for the buck doing mod.

Also remember if you get external Dac you have extra expense of another good AC cord, digital cable, and extra shelf space.