B&W Nautilus 802 compared to 804

I second the subwoofer recommendation. N802's take some breathing room and serious amplification to really sound their best. Think 300 watt monoblocks. Unless your short term upgrade path is to replace the integrated with seperates I expect you might end up very dissatisfied with the N802's. A properly choosen subwoofer will allow you to retain the strengths of the N804's and add the well controlled bottom end that will complement your existing system.

I think the nu vista would easily power the 802s.I have powered much more difficult loads very easily to extremely loud levels with that amp. Oh and BTW the nu vista puts out 310 watts a channel so its more than those monoblocks!!! It should not be an issue as to whether or not it will power them. I would, however, change to different speaker like dynaudio confidence 5s. I have listened to the two extensively and there is no difference which is better. Guess which ones i bought..... There are many other better speakers in the 5k used range than the 802s and the nu vista can power anything out there so there is unlimited choice. I would change manufacturers. I hope this helps, but somehow i dont think you will consider other speakers...

how do you add a sub to the 804's? where do you wire the sub to?

The REL's contain explicit instructions for connecting to your system, basically you take their proprietary cable with three colored wires at the amp end and hook the red and black to your right channel + and - and then the yellow to your left channel + and the sub takes the exact same signal that is going to your speakers for effortless blending and matching. The REL is absolutely fantastic, I just bought a tiny 15" cube, the REL Q201E, and cannot believe how tuneful, rich, and musical the bass and midrange now sound w/my tiny Mirage monitors. I cannot overestimate the difference a REL, any model, will make in your system. --Sarah

As Sarah is saying, the REL connects to the speaker terminals on your amp. So they receive the same signal as your N804s and will integrate perfectly. You will not know the sub is there until you turn it off. Many subs have a crossover that cut off and replace the low bass from your main speakers. RELs are designed to let your main speakers run full range as before. They fill in the bottom below what your main speakers can produce. So if you like the sound of your N804s and your system as a whole, this is a perfect way to add what is missing. RELs are not boom boxes. They are as tuneful as your main speakers. And yes, when I said two subs above, I did mean one for each channel.