[robrob]

I have created a JavaScript webpage calculator and Excel spreadsheet that will help you optimize a headphone resistor network interface for your headphones and your speaker amplifier.

 

 
The Head-Fi Wiki article is here.
 
Instructions for the webpage are just below the calculator itself. The Excel spreadsheet's instructions are on its page 2.
 
I hope you find these tools useful.
 
Rob

 

[robrob]

I have recently published a free headphone calculator for the Android. It has power calculator and resistor network calculator pages along with help pages.
 
Rob
 
In the  Google Play Store search for 'headphone calculator' or Rob Robinette.
 
You can also download it directly from the Android calculator home page.