Was there any build quality differences in the Dynafex DX 1, Dynafex DX 2 or Dynafex DX 3 units. I am am aware that the DX 1 has more settings and is a mono unit, that the DX 2 is a stereo/mono unit and the DX-3 only has one Threshold and Brilliance adjustment knobs.

Does one of these sound better than the other? I have a DX-2 I recently purchased at a rock bottom price. It seems to function as described the manual but listening through it I notice loss on the high frequency end of the spectrum.