Reddit mentions of Voodoo Lab Pedal Power 2.1mm Current Doubler Adapter Cable

You can try a config with a few of these. If I were doing it, I would hook up one 250mA output with a 100mA out, and then combine two 100mAs with a second one. this would effectively change your board to have the following outputs:

• 9v 100mA (3 of these)
  
• 9v 200mA
  
• 9v 250mA
  
• 9v 350mA
  
  So you can hook your three high current drawing pedals to the three higher current outs, and then use the remaining outputs for your low draw pedals. This is in theory, I've never done this, but mathematically this is how that would work. You could also double off of another 100mA output for the other 250mA to give you more headroom.
  
  EDIT: I am now looking at the power supply you listed and it says there are two outs that are 300mA, not 250, unless there's an older version I don't know about

It works great I’ve been using for several weeks. Posted a link to 2.1 to 2.5 Adaptor above and here is the current doubler I mentioned.
Voodoo Lab Pedal Power 2.1mm Current Doubler Adapter Cable https://www.amazon.com/dp/B00FNY74V6/ref=cm_sw_r_cp_api_i_qwolDbRHGZBA5