Help wanted

Have been without music for about two and a half years. I left my house in Southern California and moved to the state of Idaho. Had to sell my stereo  and bought a home in Idaho. Saved a few dollars and putting together a new stereo. Want to know how I can improve the sound with a very limited budget about 1500 dollars. My current equipment

Line magnetic 845 IA
LKS dac 004 with USB upgrade and modded by EVS
Proac d20r speakers
Acoustic Zen tsunami III PC
Acoustic Zen absolute copper
Acoustic Zen hologram II biwired speaker cables 
Curious evolved USB cable
Upgraded my computer with a titanium fanless 650 power supply

Listening Room is 15 x 20 and has carpet over raised floor. Speakers will be 31 inches from front of speaker to wall behind them. Speakers will be 8 feet apart and 8 feet to listening area. From listening area to wall behind them is roughly 5 ft and 6ft to side walls.

Still not listening to music as I am waiting on my DAC and speaker cables to arrive. Have $1,500 to spend on one of the following either a power conditioner a subwoofer or a preamplifier. Any help will be greatly appreciated. We'll roll some tubes after listening to the stock amp. Thank you for your time.

To be honest I’d wait until you get everything set up and working before you make any decisions. You may find your happy with what you have.

Not sure why you need a preamp with you integrated, your integrated is quite nice. I loved tube amps on my Proac's when I had them. 

Power conditioners - regenerators work well in areas with poor power or much noise on the power line, but if it was my money I’d wait to see how everything sounds and upgrade what’s needed then.
As stated before, get the system set up and working first. Listen to it as-is for awhile then evaluate. My guess is that $800 worth of room treatment will improve your sound more than $1500 of anything else.
As the posters mentioned above, wait and see, but unlike some I think subwoofers are just plain fun, especially if you hook up your system to your DVD player and TV for audio to enhance video.
Listen to your system when it's complete. You may just like it as is. There is also the possibility that you may need some acoustic treatments to bring everything together. My advice would be to NOT let that money burn a hole in your pocket. 
I agree with everyone above often a bit of patience not only saves money but gets us the upgrade we really need. And congrats on the new system it looks great!
I want to thank everybody for their input so far and yes indeed I do need to exercise a lot more patience.Its just great to be back and talkin audio again.

Ericsch my speaker measurements are from the center of the woofer to the center of the woofer. Sorry I should have made that more clear in my original statement, they are actually seven feet apart, my bad!!! Once I get sound I will move the speakers as needed could be 8 feet apart,could be 9, could be 6, I'll try them all thanks  again for your help I really appreciate it.