Hi Demonicdanny
As per specs of X1000 the AVR outputs 80w per channel at 8 ohms load across all frequencies between 20hz -20khz. It supposedly outputs 120w at 6 ohms load at 1khz.
You need to go for speakers which are minimum 6 ohms or above to match well with the AVR. If your room is large, you would need to consider to have Floor Standing or Towers as FRONTS, a decent centre speaker as it would do most of the work in terms of dialogue delivery for movies and concerts and a good punchy subwoofer as this would add the true color to the whole setup. The rear speakers can be decent bookshelf speakers....
Depending on the available area in your room, you can opt for Bookshelf speakers or Larger ones...if you are inclined to use satellites, you may end up increasing the volume to hear them clearly which may cause some amount of jarring.
Denon pair well with Polk speakers and you should go to Pro FX and see the available models that appeal to you in looks, performance and ofcourse budget.
The Polk RM6750 speaker package is decent if you want to add it to the Denon X1000...depending on what levels you hear your music and watch movies you could perhaps consider the same.
HiFi Mart also has some decent speaker packages available which you can perhaps consider.
Boston Acoustics SoundWare XS 5.1
Boston Acoustics A 2310HTS Home Theater Speaker Package
Wharfedale Obsidian 600 Home Theatre Package
You can also do a mix and match between different speaker brands...all you need to keep in mind is the impedance should be same or higher than the AVR and the speaker needs to delivery ..rather perform across most of the frequencies between 20 hz - 20 kHz if not all!
AVRs will change with new features and formats...you need to invest wisely in a good set of speakers as a one time to last you for minimum 5 years if not 10. You may want to increase your budget to get good speakers....
There are tons of user reviews and videos available over the internet which you can refer to before taking the final decision...
Hope this helps...
