I purchased a pair of N805sigs about 3 months ago. If contains a different tweeter, woofer and crossover than the "stock" N805's. Also, as dave mentioned, the finish is different. It does not share any drivers with the N802's. The surround is different on the woofer and the tweeter is a updated design.
I owned a pair of "stock" N805's for a few years. Recently, I decided to upgrade and listened to speakers from about a dozen different manufacturers. The 805sigs were not even on my list of speakers to audition. I was at a dealer to hear the new B&W704's when he suggested I listen to the sigs. I was blown away. My wife, who is not an audiphile, was also blown away. She hates black (grey tigers eye)speakers, but said the sound was "good enough" to look the other way. I am hearing things that I never hear on the "stock" 805's and the bass, mids and highs are all smoother and have a "rightness" to them. Worth the price of admission!
Good luck,
I owned a pair of "stock" N805's for a few years. Recently, I decided to upgrade and listened to speakers from about a dozen different manufacturers. The 805sigs were not even on my list of speakers to audition. I was at a dealer to hear the new B&W704's when he suggested I listen to the sigs. I was blown away. My wife, who is not an audiphile, was also blown away. She hates black (grey tigers eye)speakers, but said the sound was "good enough" to look the other way. I am hearing things that I never hear on the "stock" 805's and the bass, mids and highs are all smoother and have a "rightness" to them. Worth the price of admission!
Good luck,