Neighbor Complaining...

Anyone know where I can get a cheap big rug and how to hang it?

Well ikea of course! Go to any carpet place and see if they seel those clips they use to hang the rugs they sell. but the rug will only cut out some the reflective sound and the high frequency stuff at that.

Absorbing low frequency sounds require many inches of thickness. Acoustic treaments can get pricey but could give you piece of mind of happy neighbors. Though I doubt if your small speakers are completely pressurizing your loft with bass so maybe it's just the echo/reverb that is affecting them?

ed

I found switching to monitors helped. Less bass energy and decoupled from the floor.

Keep those Quads at least 2 feet from back wall and 1.5 feet from side walls. More the better in your case. The Quads have solid bass for their size.

In the past, I've had great luck convincing NEW neighbors that I am partially DEAF, which is why it might be a little loud.
Nobody thinks to ask what a deaf person is doing with a good stereo!