INPUT:
ffmpeg \
-i "media/IN.mkv" \
-i "irs/dh++.wav" \
-i "irs/atmos.wav" \
-i "irs/dtshx.wav" \
-i "irs/gsx.wav" \
-c:v copy \
-c:s copy \
-c:a libmp3lame -q:a 0 \
-filter_complex "[0:a]loudnorm[norm]; \
[1:0]pan=16c|c0=c0|c1=c1|c2=c8|c3=c7|c4=c6|c5=c13|c6=c6|c7=c13|c8=c4|c9=c5|c10=c12|c11=c11[hrirs0];[norm][hrirs0]headphone=map=FL|FR|FC|LFE|BL|BR:hrir=multich[hf0]; \
[2:0]pan=16c|c0=c0|c1=c1|c2=c8|c3=c7|c4=c6|c5=c13|c6=c6|c7=c13|c8=c4|c9=c5|c10=c12|c11=c11[hrirs1];[norm][hrirs1]headphone=map=FL|FR|FC|LFE|BL|BR:hrir=multich[hf1]; \
[3:0]pan=16c|c0=c0|c1=c1|c2=c8|c3=c7|c4=c6|c5=c13|c6=c6|c7=c13|c8=c4|c9=c5|c10=c12|c11=c11[hrirs2];[norm][hrirs2]headphone=map=FL|FR|FC|LFE|BL|BR:hrir=multich[hf2]; \
[4:0]pan=16c|c0=c0|c1=c1|c2=c8|c3=c7|c4=c6|c5=c13|c6=c6|c7=c13|c8=c4|c9=c5|c10=c12|c11=c11[hrirs3];[norm][hrirs3]headphone=map=FL|FR|FC|LFE|BL|BR:hrir=multich[hf3];" \
-map 0:v:0 \
-map [hf0]:a -metadata:s:a:0 title="Dolby Headphone DH-2 Cinema"  \
-map [hf1]:a -metadata:s:a:1 title="Dolby Atmos 7.1 Headphones"  \
-map [hf2]:a -metadata:s:a:2 title="DTS Headphone:X"  \
-map [hf3]:a -metadata:s:a:3 title="Sennheiser GSX 7.1 Binaural"  \
-map 0:a:0 \
-map 0:s:0 \
"media/OUT.mkv"

OUTPUT:
[AVFilterGraph @ 0x154fb40] No such filter: ''