Don't ponce around with muslin or spice balls, do what the BIRs do, blend the damn things in with the base! Yes, they do do this, because there ain't a chance in hell they're going to try to fish a few cardamoms, bay leaves, and cinnamon sticks out of those bloody great pots they use!
Or, alternatively, boil up the whole spices in a separate pot and add this 'spiced water' to your base.