Q:
I recently purchased a new Xone:42 mixer from an authorized distributor. While I love the mixer, I had a question as to whether my filters are working correctly;
- When I engage the Hi-Pass Filter (HPF) for any input channel, with the Resonance control turned to 'MILD' and 'FREQ' set at 20Hz, it immediately lowers the bass. In other words, there is a mild but noticeable effect on the sound, even before ‘sweeping’ the filter.

Is this normal, or should I have my unit replaced?

A:
This is quite normal; when the filter is enabled, the signal is physically switched through different analogue circuitry and the character of the sound changes as a result.
This is noted on p.14 of the XONE:42 User Guide, under 'Resonance Control', where it states;

"...the control ranges from 'mild' producing a very subtle effect, to 'wild' producing a dramatic phase effect with feedback just short of oscillation...".

So, there will always be some effect to the sound of any signal routed to the VCF stage, even where the RESONANCE control is set to MILD.