I am using a Babyface with latest drivers and Totalmix FX, the Totalmix FX Version says 0.989. While re-calibrating my monitor setup, I came across a strange thing which I do not understand.

In Totalmix FX, when I am routing 2 signals of the same level to one hardware output, I expect at the hardware output a level increase of 6 dB.

Indeed, when I output two -14 dB signals on 2 different software outputs, and I route those software output channels to one hardware output, I am getting a -8 dB output signal - a 6 dB increase, as expected.

However, when I send a -14 dB hardware input and a -14 dB software output to one hardware output, what I get is a hardware output level of -15,7 dB, instead of the expected - 8 dB.

When I mute one of the routed channels - either the hardware input or the software output channel - then I get full -14 dB at the hardware output, and when I unmute the one channels which was muted, the signal at the hardware output gets DOWN to -15,7 dB.

My Totalmix setup uses no FX, no loopbacks, and faders of all routed channels are set on 0 dB, of course.

Could somebody please explain to me what is going on? Thank you! I couldn't find anything about this effect in the docs.

regards, Mikael