The one with the stacked treble/bass knob. I heard that it doesn't have the treble roll-off function in passive mode that the other glockenklang OBP's have. Does anyone know whether this is actually the case? Bestbassgear.com seems to confirm that the 4-knob version doesn't have passive treble roll-off, but on Thomann.de it is described as being featured, and glockenklangs own website didn't clear up anything for me. Help would be appreciated!