I recorded audio form my synth but when i play this and orginal midi track at same time ? these have random latency in between these. I know latency is normal and can be compensated what in can when latency is totally random. And greatly audible. Soundcard & Midi interface is Emu 0404 ja Syntheizier is Yamaha S30. And operating system is Windows XP Pro.
You should be able to modify the size of the buffer using either ASIO panel, E-MU panel or the panel of your software
Try to have a buffer between 15 and 30ms