Interesting looking products. I'll look into these more, i've never heard of the digiZoid before. I have no idea what this would be like on the quads. can you tell me more about your experience with the digiZoid stuff?
The quads reproduce sound 4hz lower than the human ear can hear. I can easily give myself too much bass (didn't know that was possible) when tweaking with the software EQ. Not because the bass is distorting, but just that it's so strong it needs to be balanced down. This is not something i'm used to with any other headphone, usually the capabilites of the drivers simply fail to perform adequately and I just never get the bass i'm looking for.
For example, If i use the same tweaked EQ levels I use for my Quads on my Bose QC15s the distortion is just horrendous, they simply can't handle those frequencies at any volume above minimum. So far on all the tracks I've tried, the quads let me set my EQ to whatever I want it at and produce the sound as I tell them to without distortion.