Speakers

The hard surfaces are going to be a problem.Give some serious thought to room treatments.GIK has very attractive options that fit in with any decor.They are light enough to be stored away easily between serious listening sessions if that's a factor.Check out their website - GIK Acoustics

My problem in upgrading my stereo has been getting the speaker/amp combo right with the room. I hear a system the wows me in the showroom then I get it home and it sounds no better than what I had, There's too many variables that I can say from my own experience gave me fits. The moving co's made some money coming to my address to pick up the latest speaker to fall short. I finally went with self powered dsp's and it's early in the game but so far so good. 

Right now, your Speakers are nowhere near reaching their potential for better performance (meaning you truly haven’t heard what your Speakers are capable of yet). The only reason to change the speakers is if you don’t like or are offended by their tone.

It would be like having a Martin Guitar and trading it for a Taylor or Gibson. Do you want your guitar to sound better? Hand it to a better player. In this case, put better Electronics and cabling in front of those speakers and help them reach their true potential.

After you live with that a while, then you might want to explore finding a better sounding instrument (Speakers).

Here’s a pair of Joseph Audio Pearls in your price range. They will blow away your 804s in every conceivable way.

https://www.usaudiomart.com/details/649537368-joseph-audio-pearl/

Or for quite a bit less these AZ Crescendos would also be a big upgrade.

https://www.audiogon.com/listings/lis9g2b0-acoustic-zen-crescendo-mkii-full-range?refsource=hifishar...

Still not sure what "upgrade" means to you. What do you think could be better (or just different) -- bass, midrange, highs, volume, clarity, dynamic range, imaging, physical appearance? That list could continue, but hope you get the idea.

In response to everyone, room  acoustics will be hard surfaces speakers will be on long side of wall I have had my B&W 804N for 14 yrs just want to upgrade Really looking for a good match with NAD M25 amplifier don't want to waste money on to much speaker  2ch. music only.

Speakers on short or long wall?

Non-biased opinions here? Good luck.

To put it another way, what about your current set-up is falling short and needs to be improved?

what kind of sound are you trying to achieve? Prepare to get many comments suggesting room treatments.