Amplifiers that can power loudspeakers without sounding terrible take up a certain amount of space. That said, many smaller/cheaper alternatives end up getting

Amplifiers that can power loudspeakers without sounding terrible take up a certain amount of space. That said, many smaller/cheaper alternatives end up getting packaged in larger form factors than they need so as to avoid looking cheap. A powerful receiver is the backbone of your audio system, though, and so if you want good sound, eventually you'll just have to give in and buy one. Get a nice shelving unit to put it in and make it part of your room, not something to hide.