Dirk Lance -- Ex-Incubus Bassist Digs in for Divorce

Dirk Lance -- the original bassist for the band Incubus -- is about to be a single man ... his wife is pulling the plug on their 7-year marriage.

According to court docs filed in L.A. County Superior Court, Lance's wife -- Emily Felz Hansen -- claims the couple separated on August 15 ... and blames the split on irreconcilable differences.

Lance -- real name Alex Katunich -- married Emily back in 2004 ... they have a 1-year-old daughter together. Emily is asking for joint legal custody of the child. She also wants primary physical custody ... with Dirk getting visitation rights.

The docs show Emily is also asking for Alex to foot her legal bills.