Well, I worked a long time withe the CS1x which it's nearly the same and I never had problemes using it withe an external Sequenzer or Logic Audio for example...! You have to know, that, if you using the Cs1x/Cs2x in the performance mode, you can't play any sounds on the Midi channel 2 to 5, put the next sound in your external sequenzer to midi channel 6 and everything is working...! From channel 6 to 16 you can only use XG-Sounds!!! This is because the first midi channel can play 4 Voices simultaneous. On the other parts from 6-16 are only one voice! This is hard to understand for some people, I know! If you want to use on every Midi Channel 4 parts simultaneous then you have to buy the Cs6x, which is able to do that and I am happy with that!!