I would say that for multichannel DVD-A's and SACD's there's really a bonus with full range speakers all over (although there's always a question about how good the multichannel mastering really is and if all that sound spinning around is going to have a positive or negative impact on music perseption; some titles are ok, some are a disaster ...). For movies I'd rather say it doesn't really matter that much if you have fullrange or small as rears.

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