For me it's a high-quality video image. I’m fixing on the words "absolutely essential," and, for me, a good-quality video image is absolutely essential. When it comes to home theater, I'm more sight than sound oriented.

Roger Kanno:

I would have to say that there are actually two equally important aspects to great home-theater sound: dynamics and high fidelity. Sure you can have a good home-theater system that can play really loud but doesn't quite have the fidelity to unravel all the nuances of a movie soundtrack. You can also have a satisfying system that may be very refined with great resolution but does not have the oomph to really fill a room with the sound pressure needed to kick you in the guts like real home theater should. However, when you have a home theater that has both of these attributes, the experience is truly incredible. For instance, in one scene you might hear what sounds like wind and individual leaves rustling all around you while in the next scene a huge explosion will fill the room and literally suck the air right out of your lungs while you can still pick out other more subtle sounds in the audio mix.

But alas, this quality of sound does not come cheap. Processors and multichannel amplifiers capable of this level of performance are in the "multi-kilobuck" range, and a comparable speaker system would cost even more. This is where I feel the two worlds of high-end audio and home theater meet to provide a visceral and involving experience that can be truly thrilling.

Anthony Di Marco:

Bass. Firm, tight, round, voluptuous, and, above all, accurate bass is absolutely essential to not only music but home theater as well. Without the foundation of low frequencies to build upon, voices, instruments, and explosions would lose much, if not all, of their impact. A simple experiment would be to shut off your subwoofer or dial down the bass portion of your system. Palpability of midrange, the strong snap and punch of a drum, or the nerve-racking, visceral concussion of an explosion would sound limp and tinny.

That's not to say you should go out and look for the biggest boom-boom box for your buck. Finding a subwoofer(s) that works well in your room is usually the most difficult part of building a home theater. Each room has its own unique affect on the way bass behaves, and it takes some education to learn what to look for. Taking a few minutes to read Home Theater & Sound’s technical articles is a good place to start in your search for supple, luxurious, invigorating...err, you get the picture.

Doug Blackburn:

I'll go for real full-range or near full-range bass from one or more subwoofers. Without that, you're just listening to TV with more speakers. Unfortunately the bass is also one of the most expensive things to get in a good home theater. Luckily, there are very good subwoofers selling for as little as $500 (Hsu for example), but most subs under $800 have some serious limitations. Most people probably think that a large TV -- 32" at least and 35" or 36" more preferably (as a minimum) -- is required for home theater. I would put the bass requirement ahead of even that. I would rather live with a competent 27" TV and great bass than a 36" TV and compromised bass performance.

Vince Hanada:

In my opinion, in order to have great home theater, the most important aspect of a system's performance is the ability to create a believable soundfield. This soundfield should surround you and should be so seamless that you don't hear the speakers -- only sounds between and around them. The speakers and their placement in the room are probably the most important parameters to create this believable soundfield. Speakers with the ability to image well are essential in the front soundstage. Dipoles, bipoles, or quadpoles on the sides and rear help achieve this believable soundfield in most rooms, although direct radiators in some rooms can also work well. Good video quality, bass to shake your pant legs, and deafening loudness are great characteristics to have, but these performance aspects are simply the icing on the cake.

Doug Schneider:

Many think that the surround effects are the most critical for home theater. I don't think so. Rather, I think the single most important criteria is frequency response. Sit any novice down in front of a home theater and, sure, they'll be impressed by what's going on around them, but more often than not what they'll notice first is the highs, lows, and everything in between. Many people are not used to hearing a good system with wide-bandwidth response. That, to me, is what's key and is why I recommend to people that if they cannot afford a good surround system, start with a good stereo system. In fact, once you hear a movie in stereo through a set of full-range, or near full-range speakers, you may not even want surround all that much.

Jeff Fritz:

Whether I’m listening to a reference-level system or a budget setup, the speakers must be calibrated properly for the listening position. It always amazes me that performance can be improved dramatically by dialing in the system just so. This will garner a realistic soundfield and seamless surround performance. After that, the quality of the speaker system is probably the limiting factor. Having a full-range, transparent system that doesn’t compress when fed a dynamic soundtrack is key.