Basic question about sensitivity

@elliottbnewcombjr , if my memory serves me (and it may not), ARC was claiming that the VTM120s with four 6550s in each one were making 100 wpc.

In retrospect, I think that they sounded great. They could rock the house or whisper real quiet or just play sweet and smooth. My aural memory is probably not the most accurate, but now I think that they probably outperformed my current Cary V12 that I replaced them with. What I did not like about them (and I am not at all saying that this is applicable to all ARCs or even all VTM120s) was their reliability (or lack thereof). Every so often (and by that I mean way more often than once in a blue moon) on start up one of them would blow a grid resistor. It usually sounded like a lady-finger firecracker going off, or maybe not quite that loud, but it meant I had to get whichever was the offending amp down, put it on a table, pull the bottom panel off, and desolder the blown resistor from the circuit board and resolder in another one, of which I started keeping several on hand (I seem to remember them being 75 ohm resistors). It wasn’t the end of the world, but it wasn’t a great way to start a listening session. It got to where I would cross my fingers and grit my teeth when I flipped the switches. And most of the time I got my wish and they started up without incident; but a failure happened often enough that it was always on my mind.

By contrast, that Cary V12 that I replaced them with is super reliable. Occasionally it will blow an AC power fuse when I turn it on. Early in its life one of the output tubes went down, and a few years ago one of the signal caps failed, but all in all it is a very reliable amp, and I have had a lot of fun with it over the years.

Given that my 805s are going on 30 yeras old, and taking in account for inflation and technology, how far do you think I'd need to go to make a significant upgrade?

Any significant upgrade with modern speaker can turn out a downgrade so take that into consideration. It was the best monitor they've ever produced. They're easy to drive with tube amps, because of their stable impedance. 

I went back and had a look at John Atkinson’s measurements for your V12. On paper, even accounting for the 4 Ohm tap, they don’t look like an ideal match for one another - due to the tough load and limited efficiency. However, a lot depends on what kind of music you listen to and what volume you listen at.

Wow, thanks, @yoyoyaya ! I suppose I should be looking at something with similar specs to my current but aged 805s (sensitivity of 87 or greater and 8 ohm minimal impedance). My online window shopping I have been doing at Music Direct was starting to focus on the Wharfedale Elysian 1 with AMT tweeter, but considering the specs, a nominal impedance of 4 ohms and minimal impedance of 3.8 ohms (sensitivity 89) that impedance might make them tough for the Cary.

I will say that right now, and probably for some time to come, my listening is happening at a fairly near field in a small room, and usually consists of smaller jazz or folk presentations usually featuring a female vocalist and I am not cranking it to excessive levels.

I wonder if Klipsch should be on my radar at all? A while back ago in another thread I had asked about impressions of the Mobile Fidelity Source Point speakers, and @soix had recommended Joseph Audio Prisms and even sent me a link for a used pair. I haven’t contacted the seller about an audition period yet, but I wasn’t ruling them out, either.

Any significant upgrade with modern speaker can turn out a downgrade so take that into consideration. It was the best monitor they've ever produced. They're easy to drive with tube amps, because of their stable impedance. 

Thank you for responding @czarivey  , to be totally honest, I do not have a great understanding about this hobby, but I suppose in one respect, I am like most everybody else, and always wondering what the weak link is and what it would sound like if I upgraded past it.  When I bought those B&Ws way back in nineteen-ninety-something, I was so happy with them that I didn't even think about them as a weak link and I kept on upgrading the electtronics in front of them, and lately I was thinking that I had the front end to speaker ratio skewed.  And that is what prompted the recent "windo shopping" I have been doing.

@OP There is no problem using a 4 ohm speaker with your V12 as long as the speaker is fairly close to it's nominal impedance. But you probably want something in the region 87dB. But if you are sill happy with your 805s, I wouldn't be rushing out to change them.