just to add my 2 cents...i have owned both the 805s and 804s. my room is 16 x 22. I felt the 804s was definitely worth the upgrade because of its fuller sound. I listen to low volumes, usually around 60-70db so low level detail is absolutely critical for me. I felt the 804s performed well in this area. Even though the 805s is nice, when pushed with challenging music, it can sound strained and thin, as if it is trying too hard to keep up, which it is.
Give the 804s a good amp and you should be very happy...also think about room treatments, especially in a square room.
Give the 804s a good amp and you should be very happy...also think about room treatments, especially in a square room.