fix downmix in pyaudio3dtools as well

) -> np.ndarray:

    """Convert a multichannel signal to the requested output format"""

    # MC -> LS

    if out_spfmt.isloudspeaker:

    if in_spfmt.name == "STEREO" and out_spfmt.name == "MONO":

        MC2LS = np.vstack([[0.5], [0.5]])

        return in_sig @ MC2LS

    elif out_spfmt.isloudspeaker:

        try:

            MC2LS = IVAS_MC_CONVERSION[in_spfmt.name][out_spfmt.name]

        except KeyError: