fix evs_lfe_9k6bps_nb for Multichannel

        # in case of LFE 9.6 kbps NB processing strip any "-max_band XX" from cmd.extend and amend by "-max_band NB"

        if proc_chan_lfe_9k6bps_nb is True:

            if self.cod_opts:

                cod_opts = self.cod_opts

                cod_opts = self.cod_opts.copy()

                # for finding index of max_band entry use lower case version

                cod_opts_lower = [x.lower() for x in self.cod_opts]

                if "-max_band" in cod_opts_lower:

                    idx_max_band = cod_opts_lower.index("-max_band")

                    # use original version and not lower case version due to possible paths in there

                    cod_opts[idx_max_band + 1] = "NB"

                else:

                    cod_opts.extend(["-max_band", "NB"])

            else:

                cod_opts = ["-max_band", "NB"]

        else: