I gave the GND Defender a solid dozen a/b tests on my WA22 tonight.
Sad to report no audible difference in background hum versus straight cable without it. Granted my hum problem is what I might call a 3 on a 10 scale on Hi Z and a 1.5 on Low Z. So I don’t really complain. And with any music I don’t notice it. Just wish it were gone.
Tweak search goes on. Defender gets returned.
Well, that's disappointing. I'm continuing to test the GND Defender, DC Blocker, new IEC cable, and different power supplies. I've also emailed iFi to get their input.
Reply from iFi:
Thank you for contacting us regarding your GND Defender and DC Blocker. We would begin by noting that, based on the information you have provided regarding the hum in your audio setup, the DC Blocker appears unlikely to provide any benefit to your setup. The DC Blocker is intended to remove DC on the mains, which can cause mechanical hum in the transformer of an amplifier. When DC power reaches a transformer such as those found in amplifiers, it causes excessive vibration in the transformer, which presents as a mechanical hum from the transformer itself. You would therefore expect to be able to hear this hum coming from the headphone amplifier unit itself, rather than through the headphones. If you are not hearing a hum from the headphone amplifier unit, then the DC Blocker will not resolve the issue.
With regards to the GND Defender, we would note that this device is intended to break ground loops, which in turn can reduce or eliminate ground loop hum. Please note, however, that if there are still multiple earths within your audio setup, you can still encounter hum until you are left with only one earth connection in your audio setup. Additionally, the GND Defender is unable to remove hum caused by the lack of an earth connection in your audio setup. A quick way to identify that your setup does not to have an earth connection is to touch a metal component within your audio setup and check whether this has reduced or eliminated the hum. If it has, then you will need to add an earth to your audio setup, which can be done using our Groundhog+ kit.