When I connect my d4 with the usb so I'm using the dac+amp, it makes bass sound crackly, I don't know how else to explain it. If I'm using just the amp without the dac, this problem doesn't happen. Is this known to happen with the d4? If so would I be better off with an e9+e7? I'm using ultrasone HFI-780 if it makes a difference.













