Designing an output pad for the A12

I have been thinking about designing an output pad for the A12, as I love the sound but it is a little hot on drums. I would like to design an output pad to take off 12db. I found a website with an explanation but I have a few questions. Would I need to use 1/4watt resistors or 1/2watt resistors? What is the output impedance of the A12?
Thanks for your help!
Thanks for your help!