To Sub or not to Sub...?

Some speakers (usually very expensive) really don't need subs or a sub makes very marginal difference. Then there's the question of power. Bass frequencies require lots of power while higher frequencies do not. By adding a sub with active cross-over and its own amp, you free the other amp to reproduce just the less power demanding higher frequencies. Two benefits: more head room less clipping and usually more phase coherence due to the coil-less electronic cross-over. Bottom line--much clearer sound with the subsonic signature alluded to above. If you need bass, this definitely the way to go.

Definitely Sub. Onhyw61 is correct. All instruments have a larger sound signature than the note being played. The same reason a large regular speaker will sound fuller and richer that a small one. The Sub will fill in the lower half of the sound signature that most all speakers lack. It is amazing how a good sub will improve the detail and space between all of the instruments (even wind instruments). After I got one (a REL Storm III), I quickly discover what I was missing in the lower octaves. Recordings that once had strings playing low (Bass & Cello), all of a sudden had the Bass and Cellos clearing playing different notes in harmony.

Sub ... no doubt. I agree that it is the single most difficult thing to add to your system and if the rest is marginal at the start you'll be throwing gas on a fire. The thing that's usually missing for me from real live music in the hall to ANY system is the signature of the room the recording was made in. I made lots of recordings in college ... choirs, orchestras, soloists ... all types of groups, all kinds of equipment ... ALWAYS, I would find that I couldn't 'feel' the room unless I had a system in front of me with true full range extension.

Before you discount my college recording experiences, know that the department head and guru of all things audio at the school was a guy named Gary Galo ...

Hey guys forget about how low/HZ certain passages go. Especially if you own monitors, there is FULLNESS you can achieve by intergrating a sub. I own a pair of Sonus Faber Electa Amatours which go down to 45HZ. There really is not much recorded material that has information below that, but still a sub adds that certain fullness I'm referring to. I'm with the REL boys. I own the Stadium II which intergrates seemlessly in my system. Not many if any full range speaker can image & soundstage like a good monitor & will be as flexible as far as room dependency with the adjustments REL/monitor combo offers. I feel I have the best of both worlds by using a sub.

Lindemann is right in theory, though he forgot the lowest organ pedal point, which I believe is about 16 hz and comes at you in huge waves, more felt of course than heard and will scare the shit out of you, if it hits you unprepared. Otherwise I fully agree with the above posts. As has been stated, you need a good sub to get the feel of the space of the recording venue and also the placements of instruments right up into the midrange is vastly improved. As Kevint has put it so well: If you have one, you can't go back. Live concert goers will know, that the soudnd of a big orchestra playing full tilt can hit you like an ocean wave, both heard AND felt, coming at you on one huge continuous flow. You will never be able to get that in your own home, except with a really good sub which should go well below 20 hz and should be able to move a lot of air. Once you've experienced that, you're addicted. So caveat auditor....Cheers to all...