The Radial PhazeQ is a device that must be listened to as the specifications truly mean very little. This is because each frequency has a different wavelength and properly phase-aligning all frequencies is impossible. In other words, as you bring one frequency in phase, the next will be shifted. So what specs are important? Noise, maybe the dry frequency response… maybe the smoothness of the phase curves. But beyond that, you will have to use your ears to judge how the PhazeQ works.