I run the 803's in a 12x19 room that opens into a second room with no problem. Have listened to the 683's but found a very big difference in imaging - 803's image much better in my opinion. I also felt that the bass of the 803's was more realistic - I just did not care for the bass of the 683's. I second the above recomendation as to giving the 805's a listen - very nice speaker. As to whether you need a sub that depends on your music choice and personal tastes - for my tastes the 805's would work just fine without a sub. As between the 805 and the 803 - the 803 is more 'defined' but the 805 is better 'integrated'. Language does not really work very well in describing sound, partly because of individual tastes and partly just due to language limitations and the lack of firm definitions. In other words, the only way to compare speakers is to listen to them in the same room with the same music and with very little delay (less than 1 minute) betwen listening to speaker A vs B. In summary, the 683's lack of imaging would wear on me after a while - the real choice is between the 805 and the 803 - If you want to stay in a lower cost bracket - find a pair of 602's used - a really incredible speaker - in my opinion just a notch under the 805 and 2k less.