Yes I have a slight hum at about 75% volume but I am not sure if its the speedball or not. I do know that without the speedball my Crack was silent right up to 100%.
I only noticed the hum after soldering in a couple of 270K resistors inline with the RCA inputs as per a suggested mod in the Crack FAQ section. So I thought it was that, I plan to take them out soon when I fit a pot upgrade so will check when removed if the hum is still present.
Sounds good. That would be helpful to know as well.
Anyone else get a chance to test this out? Perhaps in particular with a set of HD-650's as the load? Turn your Crack w/ Speedball up to around 75% max volume and then all the way to 100% and let us know if you hear a hum or noise in your headphones with NO source (NO RCAs) connected.
Edited by ben_r_ - 12/31/13 at 4:22pm