The Bose aren't the right thing for a room that size. I would use gear sold at music stores, "pro" gear, or sometimes sold in the "DJ" department. Using 2-way monitors, the type with a woofer and a horn driver for mids/highs. Some of these come with pole like stand or you could hang them, a center cluster could work, or daisy chain them around the parameter. To drive them depends on the purpose, is it background music or will there be classes etc. With classes and possible microphone use I'd drive the system with a small powered mixer. For background it may be possible to use the Sony if you can work out an impedance the receiver is comfortable with driving those speakers. If the Sony has preamp outs you may want to consider a pro amp. By "music store" I'm talking Guitar Center and the like. There's probably even ways now you can use powered speakers and a computer or tablet. As far as brands Peavey or Yamaha are about the middle where Shure, JBL & Eletro-Voice would go upscale. On the cheap end some of those stores have there own house brand or other budget priced gear, Gemini used to be one such budget brand.

Any way browse the stores or website to see what's available, I'm sure you'll find some cool options but I not use home gear. If on a really tight budget use the Sony and find some used Klipsch speakers you can place in the room where available space. Klipsch are high efficient speakers meaning they will play loud with not much power the same as Pro speakers would.