< user defined
< empty arrangement
< M
< L R
< Ls Rs
< Lc Rc
< Sl Sr
< C Lfe
< L R C
< L R S
< L R C Lfe
< L R Lfe S
< L R C S (LCRS)
< L R Ls Rs (Quadro)
< L R C Lfe S (LCRS+Lfe)
< L R Lfe Ls Rs (Quadro+Lfe)
< L R C Ls Rs
< L R C Lfe Ls Rs
< L R C Ls Rs Cs
< L R Ls Rs Sl Sr
< L R C Lfe Ls Rs Cs
< L R Lfe Ls Rs Sl Sr
< L R C Ls Rs Lc Rc
< L R C Ls Rs Sl Sr
< L R C Lfe Ls Rs Lc Rc
< L R C Lfe Ls Rs Sl Sr
< L R C Ls Rs Lc Rc Cs
< L R C Ls Rs Cs Sl Sr
< L R C Lfe Ls Rs Lc Rc Cs
< L R C Lfe Ls Rs Cs Sl Sr
< L R C Lfe Ls Rs Tfl Tfc Tfr Trl Trr Lfe2
See Implementation