Good morning everyone
 I'm in the market looking for these two amps to drive my Bowers 805D3.
I would like to hear opinions of some users
Either should do the job well and both sonically are well suited to those speakers.  Not sure about NAIM inventory but M33s have a typical wait time of 90 to 180 days due to COVID.  I have a bunch on order.  

It is frustrating but that long lead time is reflective of global demand for what is an awesome unit.  Alternatively, I have listened to the Naim unit driving Focal Sopra 1s and it is lovely.  
Thanks for your answer, I wanted to know your opinion about the Hegel 390, many compare it with the M33
I had Naim Uniti Nova and can vouch for it. They are amazing for the price and they sound very musical. Don't go by their wattage, as they are very conservatively rated. They can drive most speakers with ease. They look and feel luxurious too. You might get for good discount now as they have been there for a while. 
My only doubt is that the Naim has little watage I think that the Nad has more power
That’s what I said. Don’t go by low wattage of Naim nova. They rate it very conservatively. I used them with my aerial acoustics 7t, which is 89 db, with ease (never crossed 50% on volume level: for loud music, max 55%). It is the quality of the watts and current delivered. Even their Uber expensive amps are rated conservatively on low side, but people who know the brand, understand that they deliver much higher in both quantity and quality. There is something very musically addictive quality in the nova (and Naim in general) that makes it very special. I wish I had not sold it and just kept in secondary system. I still have Naim uniti atom in other system and am never going to sell it. Just my 2 cents. But, of course, if you can listen to both and let your ears decide for you, that will be ideal. Good luck. 
I’ve heard the Naim at a local dealership, and I enjoyed it very much. I have not heard the M33, but I’ve listened carefully to another amp using the PuriFi modules, with a very positive reaction.

So, it seems to me you may have two good choices. Of course, the M33 has Dirac, if you have any interest in digital room correction, and I believe it also will manage one or two subs. It has more power, which could make a difference. Those all are nice features.

My suggestion at this point is, if you are thinking of buying new, try each one in your home and see what you think. How they work with your room and speakers (and ears) is probably going to be the key issue.
I have heard the Naim Nova and M33 at a dealer and have had a Hegel H160 in my home, but haven’t heard the H390.  The H160 had a ton of power, so I can only imagine what the H390 would be like. It’s most likely the most powerful and effortless sounding of the bunch.  If you have a big room and don’t like to feel limited I’d go that direction.  The Naim and NAD units will look nicer with their colorful displays but all three have excellent build quality. One big drawback on the Hegel is the lack of HDMI ARC which is a great feature if you are integrating with a TV.  As far as sound quality they are all excellent and in the same league as each other so it really comes down to two things - speaker synergy and features. I can’t comment on the former since none of the demos involved the 805s. I don’t think there is a wrong choice here for a flagship all in one streaming amp. 
Thank you very much for your answer, I think I am going to decide on Nad. With what speakers did you hear them at the dealer?
I don’t remember the brand, it was a 2 way tower which doesn’t really narrow it down much. I can say with confidence it wasn’t B&W or other distinct looking speaker makers.   I was shopping amps/streamers so wasn’t really paying attention. I told the guy that I had Dynaudio speakers, so he probably chose something with similar characteristics. 
Contour 1.8mk2. I’ve had them for over 20 years now.  I’ve used a bunch of amps over that time frame, but have never thought about changing speakers. I find that vintage Dyn’s have a natural sound that is detailed without being overly analytical, which is a must if you listen to a lot of live music, especially rock from the 60’s and 70’s. The last thing I want to think about is the quality of the recording, especially now that I typically stream everything. 
I am using the Naim Uniti Star with Roon as we speak, I made an offer on a used M33 and fortunately found out that it is another Hegel H390 issue where the Manufacturer stated it was Roon Ready but Roon changed their terms last year and now several devices marketed as working with Roon do not. I have had 2 H390’s and each time tired of waiting for the BS Roon "Readiness" that they were advertised to have. So be aware if you need the Awesomeness that is Roon you will not have it for an Undetermined amount of time from the NAD unit sadly. Yes I am bitter.
If you can't find a local dealer to try the NAD first, you can order from Crutchfield and get a 60 day return policy. I did that and ended up returning it - not because it wasn't good, I just liked my current set-up a bit better. I did have to wait 3-4 weeks to get it, very high demand right now. The full version of Dirac is very worthwhile and improved the sound in my room, but you need to spend some time with it.
Hello friends I wanted to ask you a question, I currently have a Rotel 1592 I know it is a different animal. Do you consider that the Nad M33 is an upgrade?