I owned the N805 and I've also had the 805 Signature on home audition.
I think it's fair to say I came to like B&W sound DESPITE what I would read on audio forums and hear from dealers (who didn't carry their speakers). There never seemed to be a shortage of people knocking B&W, claiming the speakers were "less communicative" than their competition, or that B&W was not an "audiophile" brand anymore, or that they had put looks before performance in a manner reminiscent of Bang & Olufsen.
Of course, there are plenty of positive things being said too, but where there is negativity aimed at B&W, it seems to be particularly animated. I must say that when I began seriously auditioning B&W against other speakers a couple of years ago, I had already formed a partially negative opinion without having heard a single product of theirs. I was pre-conditioned to expect relatively hard sounds, a hooty treble and plenty of detail at the expense of "musicality."
So I recall being surprised when, listening to a pair of N805 monitors and evaluating them against models from Dynaudio, Triangle, Tannoy, Sonus Faber and others (both at home and in showrooms, with recordings I knew very well), I actually liked the N805 very much.
Soon after, I bought a pair, with their custom B&W stands. After a while, I added a REL subwoofer. which I'd decided at the outset would need to be a part of the investment. Using Musical Fidelity eletronics and Nordost Red Dawn cables, I was very happy with the sound quality I was getting from my speakers. I thought I'd reached a level that suited my budget and would keep me musically satisfied for a few years. I'm not fanatical about upgrading and I don't think of each purchase as being a step along the road to some future audio-nirvana. To the contrary, I'd like nothing better than to stop buying more equipment. I listen exclusively to 2-channel, and I prefer to think of the future in terms of money spent on music, rather than on equipment.
Nevertheless, when I became aware of the 805 Signatures, I felt almost obliged to audition them. I was able to compare a nicely broken-in pair against my N805 setup in my own listening room and I remember wondering why such a fuss was being made over the new model. Certainly, there was a slightly tighter bass, but this only really seemed apparent to me with the subwoofer turned off. Used with the REL, the Signature's low end sounded so similar to the N805 as to be indistinguishable on 99% of CDs. Without the REL, the Signature low end was a very mild improvement (in tightness, not quantity), but as I considered the sub to be essential for both the Signature and the N805, the improvement was inconsequential to me.
At the top end, there was an apparent extension with the Signatures, though not necessarily an improvement to my ears. For example, sibilance actually seemed harsher on many discs featuring female vocals. I'd been told that this was an area of big improvement in the Signatures, so I was disappointed with what I heard.
Soundstaging? Ability of the speakers to "disappear"? With one particular piece of acoustic music, the Signatures created a stunning 3-D depth of sound that I simply could not reproduce with the N805. I knew that recording very well and had never heard it reproduced so well as with the Signatures. But that example was in total isolation. In everything else I played, I heard nothing to give the Signatures the edge over the N805. I was having to listen very hard for differences between these speakers. In a lab, no doubt the Signatures would measure better, but in the real world (my home), it simply didn't seem worth investing in an upgrade unless it was simply to secure the extra-luxurious finish of the Signatures (which I personally didn't like as much as the natural cherry of the N805).
Which brings us to the 805s.
Taking these out of the box, the visual differences were a lot more subtle. The most significant visual change is at the top surface of the speaker. There is no longer a hollowed-out trough for the tweeter to sit in. Instead, the top surface is smooth right across, and the tweeter stands a little higher (no longer sunk down into the hollow). This minor change is a definite visual improvement, with the tweeter housing looking more streamlined and the cabinet less "fussy." The grille is slightly more curved at the edges than before and the speaker bi-wire jumpers are slightly different (and seemingly a little less easy to fit). But please, let's not get into a discussion here on bi-wiring. For the record, my speakers are single cable bi-wired, but I hear no difference whether they are bi-wired or not.
Apart from that, I saw nothing else to visually distinguish the 805s from the N805.
But when it came to listening, there were some surprises in store. Straight out of the box, the 805s speakers were a substantial improvement on the N805 in every respect I can think of. Bass was not only more controlled, but also seemed to extend further. With or without the subwoofer, the improved 805s bass is of an upgrade-worthy level. I always felt a sub was a priority with the N805, but I can honestly say that might not be the case with the 805s. I don't know what the measurements show, but my ears tell me the sound from the 805s is more expansive and has more of a "wholeness" about it. The midrange has the same positive qualities I enjoyed with the N805, particularly with male voice, but I think any perceived change for the better in the midrange is really down to the better bass control which seems to improve everything else about the speaker. At the top end, the sibilance I noticed with the Signatures has vanished, and what sibilance there was with the N805 has been smoothed further. Yet the highs are not at all diluted. Listening to flute and female voice, I heard at least as much detail and extension as with the N805, but also a smoother, absolutely non-fatiguing sound. For me, this was a genuine, valuable improvement enough to make the upgrade essential.
And I am still talking about the 805s straight out of the box. Now, just a week later (with about 100 hours of burn-in), I don't detect any changes, but I can't say I really want to. I like what I am hearing right now.
Lastly, that 3-D depth of sound I mentioned earlier, that I coaxed out of the Signatures with one particular recording: the 805s has that quality too, but I'm hearing more of it, from more discs, and with even more depth than ever. People who believe B&W soundstaging is nothing special should listen to the 805s, urgently.
PS: I recall that when I auditioned the Signatures, I phoned B&W (USA distributor) to ask if there was something I was missing perhaps a trick of placement or bi-wiring/non bi-wiring or suchlike that would make it easier to perceive the benefits of the Signatures over the N805. I was surprised when he told me it was not worth upgrading to the Signature from the N805, but that someone buying their first B&W should look to the Signature. So I'd be interested to hear what technical support had to say to you on the attributes or otherwise of the 805s. In my opinion, upgrade to the 805s should be a priority for N805 owners.
As for Signature owners... I imagine they'd do better to wait until the diamond tweeter 805 comes out in a year or two. It's sure to happen.