Jaytor, how did you establish what’ value capacitor to use and what frequency to target?
First, you need to find out the input impedance of your power amp. My JC5 has 33K ohm per leg for the balanced inputs. Then find a capacitor value that will have a -3db point around 70Hz or so. The specific frequency isn't that important, but I think somewhere between 65Hz and 80Hz is probably a good range for these speakers. Danny can correct me if I'm wrong.
The f-3db point is calculated as 1/(6.28*R*C). Here's a link to an online calculator. http://www.learningaboutelectronics.com/Articles/High-pass-filter-calculator.php
I went with 0.068uF caps which results in a -3db point of 71Hz. I used Gen II Sonicaps that I got from Sonic Craft.
There are probably better caps (such as Miflex copper caps) if you can find them in a size that will work for you. The Sonicaps were the only high quality caps I could find that were easily found in a value that would give me a cutoff frequency in the range I was looking for.
If you have a Parasound amp, they list the input impedance of all their amps on their website.