Steam boiler pressure is set via pressure stat (unless modified for PID steam boiler control.) But boiler pressure is but one factor. Obviously how far open the steam valve plays a factor. Maybe not so obvious is what steam tip is being used on the wand. The Linea stock tip was designed for large volume of milk aka Charbucks quart to half gallon at a time size. With that tip it is difficult to get good micro-foam even for a 16oz latte and impossible smaller amounts of milk. You need a more restricted tip so you get the velocity without too much steam. Meaning less overall total hole area opening, not necessarily less number of holes. Espresso Parts NW makes a great restricted La Marzocco steam tip. Though even with that tip it's still tough to steam a no milk waste macchiato;-)
What does the boiler pressure gauge indicate? 1.2 should do well. If it reads 1.5 or more, then that could be set lower, but if it is in the normal range of 1-1.2 it is probably your tip.
i understand this is a 10 yr old post... was there ever a solution ... I have an EE 2 grp and a similar issue and question as to whether I can adjust steam pressure.