Anyone compare the B&W CDM9NT & N804

The 804 is a little more transparent and smooth in the mids and highs, the 9 has perhaps a better bass. I went with 803s.

I have the N805s but have listened to the CDM7NTs and N804. At some point I had the CDM1NTs. Anything in the Nautilus range has better definition, image, soundstage than on the NT line. Some may have more than bass than the other but overall the Nautilus range is definitely better.

The CDM Series are more forgiving of electronics (easier to power sucessfully).

Actually I did not too long ago as both were high on my list (I bought Thiel 2.3s instead and haven't looked back). The biggest difference between the 9NT and N804 to me was the far better vertical dispersion of the 804 tweeter, and the resultant more-even power response and image stability throughout the room. Surprised me as the tweeters seem very similar. They also seemed freer from the occasional 'spittiness' of the 9 HFs. The mids were full and rich on both, though the 804 bass seemed a tad more defined. Although I listened to both extensively, they were not in the same room on the same day. They would need to be for me to spend the extra $800, but the 804s were notably better to my ear.

IMO, the best speaker in the CDM line are the 1NTs. The towers do not perform nearly as well.

Listen to the CDM1NTs at your dealer and then listen to the 9NTs. Listen for clarity and imaging and the 1NTs will win every time.

The opposite is true of the Nautilus line. The N805s are better than the CDM1NTs to start with (which are better than the 9NTs), but the Naut 804s are better than the N805s (and the N802s are superior to the N804s).

If your dealer carries those speaker lines, try those combinations on the same equipment (assuming the baseline AMP, etc are up to driving the N804s). I would be shocked if your experience was not similar.