The direct box converts your signal from unbalanced to balanced. This is to minimize signal noise, and to make a hoter signal.

As far as stereo vs. mono in live settings it differs from place to place, sound system to sound system. I think this is a kind of comparing apples to oranges, since they have differen't applications. Theoretically it should sound nicer on a stereo system since the keyboard styles are mixed for stereo. But the styles are not mixed for live play. They are mixed to sound good on the small built in speakers, or the small addon speakers in the case of a Tyros. This sound is quite differen't from a PA sound. Also in a big room, you want as much of your sound to get out to the whole room. If you use stereo, people on the left side of the room will not hear a lot of the sound comming from the right speaker, so if you do stereo, they will get a different sound image than the people in front center. A live band without amplification for instance will be heard throughout the room, and may sound more "mono". So if you play big gigs, with people everywhere around you, I think mono is the way to go, to get the sound out there. If you play smaller venues, or places where everyone is in front of you, such as a concert with a stage, I think stereo is the way to go. Stereo will sound more full and balanced than mono, but it will sound quite bad if people aren't placed correctly.

Doc-Z