900srt major issue

Hi guys, 

Brought myself a brand new 900 srt in december... however i haven't been able to use serato with it as it glitches awfully through midi and timecode.... i have severe lag, audio drop outs and sometimes it doesn't even pick up that they are connected... i'm running on a late 2013 retina mbp and using latest firmware and software... this problem happens on mp3s and mp4 video files on internal and external drive... tried changing all settings reinstalling etc!!!!!!