Here, IMO, are the rankings of components of modern equipment, in order of importance to obtain excellent sound. Unfortunately, we don't always spend the money on our systems with these factors in their correct order. Please feel free to disagree or not. 1. Speakers (incl. sub)and room configuration. IMO, these are the predominant determiners of sound quality. This also includes room treatments you use. 2. The software. WIDE variations in the quality of software as well as the sound format (DD/DTS, etc) make this almost as important as speakers/room, but we can't do anything about it (except complain to studios when it's bad) so it ranks second. 3. Sound format extensions like DTS-ES, Pro-Logic II. That sixth or seventh speaker, extended surround info, can make a noticeable difference in a system. 4. Speaker placement and tweaks. Put a sub in a corner versus the middle of the floor and it effects the sound markedly. Similarly, put speakers flat on the floor, or use spikes or acoustic suspension products that damp sound or vibration also effect sound noticeably. 5. Preamplification. This can vary pretty widely, but does not have as much effect on sound as the previous two. This includes whatever equalization systems your receiver/preamp uses. 6. Power amplification. Changes the character of sound and determines how much bass authority your system has, but not as much as your speaker system. 7. Biamping and biwiring. Can have noticeable effect on sound, especially if attention is paid to the amps supporting the extreme low bass or high frequencies. 8. Interconnects. This is HIGHLY subjective but IMO, their effect is greater than the effect different speaker cables have on system sound. Try a really different material for each (Kimber style twisted unshielded versus some kind of coax) to hear major differences. 9. Speaker cable. Again subjective, but still important. Guage and the type of wire effect sound differently. 10. All other tweaks, some of which are completely unproven and prone to cause lots of arguments. I don't know if I've forgotten anything?