Hi benjamin

Since you're not a "multichannel" listener,the answer to your question is "yes" , the scd-1 is a better player.I don't know if the dacs the scd-1 is using are better or not,but the scd-1 is much better than the xa777es.As for the balanced connection,let me give you a rough guide.
Unbalanced = slightly higher noise but more "attack" in the sound.
Balanced = less noise , smoother sound , slightly less attack.
Personally,instead of the Sony scd-1 i'd go for Marantz Sa-1.imhp is a better player.