Yes, understood the 4's audio outs. It's RCA jacks I get hives with, not 1/4" plugs. USB midi is fine, just not a fan of USB audio ... but doesn't the 4 also have standard 5-pin midi connectors?

Anyway, it seems the 4 is designed so you can run a sequence on one chip while playing accompanyment on the other ... a good gigging set up. But my understanding is that there is no difference in the sound quality between the 2 and 4 since they use the same chip.

Prado