Bolivar wrote:Now this is weird. I corrected the headphone jack wiring, but the hum and phase problems persist.
If you still have a phase problem then the wiring is still not correct... Is your headphone jack a "switched" type (what jack did you use)? Did you by any chance connect the amp output and ground wires to the "switch" pins on the jack instead of the TRS contact pins?
My source is a y1 dac, I'm using Shure SRH-840 (44 ohm) headphones and I've set the gain to 4.1x. I've tested several interconnect cables. I'm utterly confused now.
Did you try a different source (i.e., CD player, iPod, whatever) just to rule out a problem with the source? Is the hum level volume knob position dependent? Does it hum when the volume is turned to minimum?