as far as i know, you don't lose any information by going with 5 speakers vs. 7. the sound to the rears is taken from what is already going to the surround speakers if movie is dts or thx ex (dolby) 6.1. there are no 7.1 encoded movies to my knowledge and even 6.1 movies are hard to find. with 5.1 encoded soundtracks, rear speaker info is matrixed from the surrounds.
7 speakers may be worthwhile in your room if you have enough room behind the listening position to properly position the rear speakers.
most people i've spoken with including robert harley (tpv), feel that there is not much difference between 5 and 7 speakers. i've wired for the 6 and 7 speakers in my ht, but have yet purachase/install them. caught audio bug instead. i don't know anyone including dealers who have 7.1 systems, so i'm not speaking with any first hand knowledge.
as far as the sub goes, all i can say is that i run a single earthquake mkv 15 inch sub in a 19x45x9 room with no problem. subs volume at 25%. room is not enclosed. (opens to another room.)
aloha keith
7 speakers may be worthwhile in your room if you have enough room behind the listening position to properly position the rear speakers.
most people i've spoken with including robert harley (tpv), feel that there is not much difference between 5 and 7 speakers. i've wired for the 6 and 7 speakers in my ht, but have yet purachase/install them. caught audio bug instead. i don't know anyone including dealers who have 7.1 systems, so i'm not speaking with any first hand knowledge.
as far as the sub goes, all i can say is that i run a single earthquake mkv 15 inch sub in a 19x45x9 room with no problem. subs volume at 25%. room is not enclosed. (opens to another room.)
aloha keith