I might consider getting an external DI box (I have Saffire Pro 40) and I it would be great if I had a chance to really hear the difference between external DI and a built-in DI input in Focusrite's interface... but generally, I think it would be great if someone who has both units (any interface within Focusrite's Saffire range, and a decent DI box) would put a practical end to a debate whether it's a plus to add external DI by doing a shootout and letting listeners decide if it's worth it...