FIG. 3 shows a further alternative embodiment wherein signal flows 1a, 1b, . . . are fed into a processing unit 9. Signal flows 1a, 1b, . . . in FIG. 3 are 7.1 audio flows. Signal flows 1a, 1b, . . . each have 8 signal flow layers 2a, 2b, In 7.1 surround audio these channels are typically used for left, right, center, rear left, rear right and LFE and height-adjusted loudspeaker signals. Each sub-signal flow 3a₁, 3a₂, 3a₃, 3a₄ and 3b₁, 3b₂, 3b₃, 3b₄ has two sub-signal flow layers 4a₁, 4a₂, 4a₃, 4a₄, 4a₅, 4a₆, 4a₇, 4a₈. Sub-signal flow 3a₁ then has sub-signal flow layers 4a₁, 4a₂ as related layers. In this embodiment this would correspond with respectively the left and right sound signal.

FIG. 3 further shows that a controller 15 reads 11 a desired ratio 13a, 13b. Ratio 13a is here the volume ratio between the first signal flow 1a and the further signal flow 1b, and ratio 13b is the reciprocal of 13a. After the desired ratio 13a, 13b has been read 11, the sub-signal flows can be merged 12 as according to the ratio 13a, 13b.