Hvad er forskellen på Surround back og Surround. Hvad er bedst. (eller har jeg misforstået noget)

Måske du kan blive klogere ved at læse denne artikel http://timefordvd.com/tutorial/SurroundSound.shtml

"THX Surround EX is the Extended Surround version of Dolby Digital 5.1, while DTS-ES is that of DTS 5.1.  The difference between the new Extended Surround formats and their 5.1-channel surround sound counterparts is the addition of a surround back channel, whose corresponding speaker is placed behind the audience.  This allows certain soundtrack effects to be presented behind the audience, thereby achieving more enveloping and complete 360° surround sound.  (Remember that in the 5.1-channel surround sound formats, the surround speakers are placed one on each side of the audience - not behind them.)  Additionally, while the Extended Surround sound format calls for one surround back channel, two surround back speakers are generally recommended for better envelopment.  Acknowledging this widely accepted industry position, some high-end receiver manufacturers have introduced "7.1-channel" capable receivers, with decoding and sometimes amplification for the two extra surround back channels. "