WITHIN THE cool, cavernous reaches of Circuit City, the winged warriors of "Top Gun" do battle, multiplied 80 times on a wall of video screens 20 wide and four deep. "Roger Rabbit" mugs and contorts and cavorts on a sole screen at its center. Nearby, a video monitor silently demonstrates itself -- electronic tickertape scrolls by advertising the TV's sleep timer, autoprogramming, picture-in-picture . . . A camcorder picks up your browsing image and flashes it back in an electronic mirror. There are halls of tape decks, rooms of speakers, galleries of personal stereos and micro-recorders. Solid, stolid wooden furniture consoles, and sleek brushed-metal low-risers. Drum machines and digital sampling keyboards. Computers and car phones. Turntablestunersequalizersamps . . .

Your eye is snared by one particularly seductive CD player. The fine print etched onto the stylishly severe matte-black cabinet informs you it is a "P-E-M D-D Converter" -- Pulse Edge Modulation Differential Linearity Errorless D/A Converter with Fourth Order Noise Sampling.

Scare me.

In the past few decades, a techno-tidal wave has swept the country -- the audio-video component industry has exploded into a $43 billion a year international operation.

Your range of options for a TV used to be simple: black and white or color? Now you start at that point (is black and white even an option anymore?) and each subsequent option offers several more: Receiver or monitor? Console or portable? Cable-ready, high-definition, wireless or infrared remote . . . .

Given the prospect of facing a dizzying blur of possibilities, an army of grinning, high-pressure salespeople, the unpredictability of your own whim and the limits of your credit cards and charge accounts, it's hardly surprising that many potential electronics consumers find themselves faced with Fear of Buying.

A terrified consumer is not the best customer. So, here's a few casual and common-sense hints to help you make your way, morale and wallet intact, through the maze of sound, light and salespeople.

Basically, it all comes down to the eternal schism between what you need and what you want.

Need: A machine that will play cassette tapes.

Want: A cassette player that decides whether it's spinning a plain or metal tape, reverses itself infinitely, skips the songs you don't like, checks your bank balance and monitors your blood pressure.

The instant you walk through the doors of a fantasy factory like Circuit City or the Sharper Image, "needs" arise unbidden -- needs you never imagined existed within you.

"This is not a necessity store," admits Pat Gulley, the affable and plainspoken manager of Video Concepts at Tysons Corner. "I mean, people can live without a camcorder. It's a desire."

Some crave all the accoutrements of desire -- the more lights, dials, and switches, the better. Others don't want to mess around -- they like it plain and simple, maybe a grown-up variation on the Kenner Close 'n' Play.

Actually, unless you're an audiophile (and you live in a detached house with soundproof walls or understanding neighbors) you probably don't need to bone up on impressive sounding terms like linearity and phase response.

But it's best to know generally what's out there and specifically what you're looking for. Be prepared.

"There's a lot to be overwhelmed by," says Gulley, as Wally and the Beaver materialize on a dozen huge projection screens behind him.

"The thing to do is figure out what your needs and desires are before you leave the house," Gulley says. "Don't go out without answering these simple questions: How am I going to use it? Where am I going to put it? What about cost? How will I finance it?" SOUND AND VISION

With the recent dramatic increase in high-quality sources in audio and video, an exponential number of new components have become available to take advantage of the sight-and-sonic boom.

But the basic building blocks of a stereo or video system are still fairly simple: Signal sources -- tape deck, CD or record player -- a tuner and amplifier, and speakers or headphones to convert it back into sound.

The turntable is rapidly becoming a thing of the past, but what do you do with all those black discs from your Wonder Years?

Put them on tape with a cassette deck. Or a dual-deck machine, which holds two cassettes at a time, allowing you to copy tapes or play two tapes consecutively without interruption. (Single-deck machines generally have an edge in performance.)

Or just replace your favorite records outright with the much longer-lasting compact disc versions, for which you'll need a CD player, available as table models that play one disc at a time, or with changers that can accept several discs at a time and play them in order or randomly. Or a portable CD player, many of which now offer features and sound quality equivalent to the bigger models and can be used both with the main unit and away from the home.

Or take a techno-step into the future, and transfer your favorites to DAT, digital audio tape. DAT decks offer the same high fidelity as compact disc players, but are capable of recording as well as playing back. Compact discs are still more impervious to wear than DAT tapes, however.

To power any one of these or a combination, you'll need a tuner and an amplifier. Or a receiver, which combines the two. Many of the new models will power and control your entire audio-video system. Make sure it has enough input and output ports to accommodate all the components you plan to drive through it.

And speakers. Two should do. But if you want Surround Sound effects (the return of that failed '70s fad quadraphonic sound in disguise) with your audio-video system, you'll want four.

Then maybe a walkabout stereo to take the music outside with you. Or an AM/FM cassette/CD beatbox. Or an in-dash cassette deck or CD player for the car . . . .

The television set has been almost universally reborn as the "home video terminal" -- now it receives cable transmissions and prerecorded programming on tape as well as the usual broadcast transmissions, and plays video games. A videocassette recorder, or VCR, is standard equipment in nearly every home these days, and is available with a variety of program-recording capabilities and a range of special effects gimmicks like slow motion and freeze frame. VHS has beaten out Beta as the standard tape format in this country. But newcomer 8-millimeter, with its tiny cassettes almost the size of a standard audio tape, is catching up.

And there's still laser disc, which is hardly out of the picture. In fact, new machines are available that will play both video and audio discs encoded with digital information.

You'll need some sort of viewing screen, of course -- either a receiver TV, or a monitor that functions only when connected to the VCR. A variety of sizes are available, from handheld Sony Watchman with its liquid crystal display screen, to Mitsubishi's 70-inch projection screen, which is nearly as big as the screen at the neighborhood multiplex. The newest twist is stereo TV. With music video a popular form, and movie soundtracks recorded with stereo effects, it's a popular feature. And they tell us that coming soon (well, it's so bogged down in standards, legislation, etc., that it may be years before we get to turn it on) is high-definition TV, with approximately 1,000 lines to the current standard 525. An intermediate step, IDTV, or improved definition TV is already out there.

And there's the camcorder, which puts the control of video programming in your hands. Shoot-and-play models allow you to play the tape back through your monitor. DESPERATELY SEEKING STEREO

Before even considering how much money you'll need to spend, decide first what kind of component or system you need. There's no point in dragging home an all-singing, all-dancing system if all you plan to do is play cassette tapes. Determine what sources you'll be using -- vinyl, cassettes, CDs -- and which components will make up your system.

It's a fact that the best amplifier and speakers in the world won't be able to disguise the defects of a poor turntable, tape deck or CD player -- in fact they'll make the inherent flaws more glaringly obvious. So if you're going to lean heavily in one area, spend more on the quality of your source components -- the equipment that actually extracts the signal from the medium -- rather than blowing your whole budget on an awesome amplifier and speakers. Even the most basic, low-cost CD player will include a variety of essential features and will deliver sterling sound. Tape decks vary widely, however, and this is where you might wish to spend for better quality.

It's possible that considerations of space, taste and plain convenience might lead you to choose an all-in-one audio package or "rack system," which often comes complete with its own cabinet. Packaged systems come in all shapes and sizes, usually providing all the items in the music line you could want. Today, that usually includes a CD player, turntable with arm and cartridge, cassette deck, AM-FM tuner, amplifier, speakers and even such ancillary gadgets as graphic equalizers (which are little more than glorified tone controls).

Aside from uniformity of design and ease of operation, the benefits of a packaged system is that it is easily set up -- you don't need any technical skills to put it together, aside from popping in a color-coded plug or two. Many systems are linked by ribbon connectors, which allow central logic circuitry to control all the system's operations from a single point.

But the biggest bonus of a rack system -- buying it all at once -- is also its biggest drawback. One of the components may be inferior, and you won't know that until you try the whole thing out.

If sound quality is really your main objective, and you have enough space to store the stuff, a system of separate components, often made by a variety of manufacturers, is unquestionably the best choice for high-fidelity sound.

Check out a variety of newspaper ads and call around -- many salespeople are happy to give advice and discuss comparisons between brands, even brands they don't carry. One company may make a dynamic loudspeaker, but a mediocre amplifier, for example. So, by mixing and matching, you're able to optimize the performance of the system. You can also leave out a component or feature you may never use. Buying a system this way also makes future upgrades easier and less expensive.

Component systems have their downside, too, of course. The different components may clash aesthetically. And there's usually more wiring involved.

When putting together a custom audio or video system, it's important to find a dealer with good demonstration facilities. This way, you'll see how different components look, sound and work together. For example, if remote control is a priority, you'll want to work out a system in which one remote will control all functions in the system. A little-known fact about the appliance biz is that some sets are twins under the skin -- the same machine, with a different brand name on the nameplate. A salesperson should be able to clarify this for you, as will any of the various publications aimed at audiophiles.

A useful source of pre-purchase information is the "Home Electronics Buying Guide," a comprehensive 300-page paperback reference published this year by Consumer Reports magazine. The guide is forthright and frank in its ratings of various electronic components and manufacturers, and its easy-to-read charts feature approximate retail prices and advantages and disadvantages of specific models. (It's $9.95 at local bookstores, or by mail from Consumer Reports Books, 9180 Le Saint Dr., Fairfield, OH 45014. Add $3 for postage and handling. To order by phone, call 800/272-0722.)

The various audio-video specialty magazines -- Stereo Review, Audiophile, Sound and Vision -- can be helpful, as well. But basically they are glossy electroporn, calculated to make you dissatisfied with your current setup and to stimulate you to buy more.

That's one of the dangers of entering Garden of Electronics. The moment you glimpse that first shiny CD, once your eyes have been opened to the limitless temptations of components, you've been infected with the Urge to Upgrade.

Madonna -- and where would she be without all those CD players and VCRs that bring her to life -- knows all about this:

Each possession you possess helps your spirits to soar

That's what's soothing about excess

Never settle for something less

Something's better than nothing, yes!

But nothing's better than more, more, more . . . -- "More," from Madonna's "I'm Breathless" I STILL HAVEN'T FOUND WHAT I'M LOOKING FOR

Once you've pretty much settled on what you want, there's just one more hurdle between you and the object of your desire: the salesperson.

Most people don't want to deal with it at all. They'd rather rush in, blurt "Just looking, thanks," finally settling for whatever model has the biggest, reddest SALE tag.

But why spend all those hundreds, even thousands, without first spending some time deciding on features and performance? A good salesperson can help.

"A salesman is labeled from the old days -- it's that 'Have I got a deal for you' thing," says Gulley. "That's probably the biggest obstacle. People walk in and I approach them and they turn around and walk out."

Gulley attributes this to Fear of Salesmen. "And to fear of confusion. Of the product. And fear of price."

At Circuit City, the salespeople try to soften the edge by calling themselves "sales counselors." The new name doesn't stop them from chasing you around the store, however.

"It's all very intimidating to people, and if you try and explain something to them, they think you're giving them baloney," sighs Scott Eberhardt, sales counselor on patrol in the CD sector of Circuit City. "But that's the only way to explain it. You have to give them a lot of support.

"Often, people want to know what brand names are better," Eberhardt says. "We don't do that. That's called 'disparagement.' You can't disparage products. We give them the facts. You sort of have to have interview skills, too, to find out what the customer's needs are and how to best fill those needs."

See? There's no reason to be afraid of salespeople. They're not out to embarrass you. They've been trained inside the company and are continually updated by manufacturer representatives, so they keep up with new features and differences between brands. No one expects you to be an audiophile. Ask questions.

But don't be gullible, either. Like fast-food cashiers pushing fries and a drink, salespeople are trained to try and push extras such as the in-store warranty. Many stores, the large chains in particular, make their profit by selling a year's service guarantee, with the cost based on a percentage of the purchase price. If you buy a reputable name brand, there's usually some sort of warranty included -- make sure to ask about that -- and many manufacturers have service representatives in your area, so sending the component out of state isn't usually required.

A final word to the wise: Don't buy something complicated if you know you'll never bother to learn it. Ease of operation is almost as important as good sound. And don't be dazzled into paying extra for features you don't need and will never use.

As one frank salesman recently told a friend who was "test-driving" a portable CD player: "It'll take you two days to learn all the features and how to use them. You'll use all these gimmicks and bells and whistles for a few hours, and you'll never use them again. Mostly you're going to pop the disc in and press play."

Come to think of it, Madonna would probably make a great electronics salesperson. Just imagine her, cruising shark-like through the aisles at your local Appliance Megalopolis:

One is fun, why not two?

And if you like two, you might as well have four

And if you like four, why not a few, why not a slew

More? SHOP TALK FOR THE AUDIO -- VIDEO NOVICE

A GLOSSARY of some of the more esoteric terms you may hear from salespeople or encounter when comparing product "spec sheets": SOUND

Bias A high-frequency voltage mixed with audio signals when recording on a tape deck -- it's essential to good quality recordings, and the amount required varies for different tape types. It's adjustable on the better decks. The higher the bias, the more sonic information that can be stored on tape.

DAC Stands for digital-to-analog converter, as found in all CD players. It changes digitally stored sound information into an analog waveform, which subsequently can be amplified in the traditional way.

Distortion In sound components, this figure indicates the degree to which the output of a component differs from the input. This number should be as low as possible.

Dolby No tape is perfectly silent. In addition to capturing the desired music signal in magnetic form, all tapes add hiss. Dolby noise reduction (a trade name for the noise reduction system invented by Ray Dolby) separates the music from the hiss. Dolby B and C operate similarly, although C is more powerful. It boosts the level of quiet treble sounds before they are recorded. Dolby DHX Pro is the name for the headroom expansion circuit, which improves the treble dynamic range of normal tape -- it has nothing to do with noise reduction.

Dynamic range This figure indicates the ability of a component to reproduce very loud and very soft sounds. Loud sounds can be limited by clipping distortion and soft ones can be masked by noise. So a large dynamic range, expressed in decibels, results in the most realistic and natural sound.

Frequency response This indicates the range of frequencies over which a hi-fi system's response is flat, meaning it recreates sound exactly as recorded. The accepted range of human hearing is from about 16 Hz to 16 kHz in a healthy young adult. Bass is from 16 to around 100 Hz, midrange from 100 to about 300 Hz, upper midrange from 300 Hz to about 2 kHz, and treble above that. That means you won't be able to perceive anything above or below those spec numbers (though your dog might, if he or she is into hi-fido).

Impedance Measured in ohms, the impedance number is important in assuring compatibility with an amplifier or receiver. An amplifier rated for eight ohms should be able to handle speakers measured at six ohms or higher.

Oversampling A form of "digital filtering" used at the DAC stage in most CD players, which prevents high-frequency distortion. This is normally detectable only with sensitive instruments, so whether a CD unit has 2X, 4X, or 8X oversampling has little real impact on the sound you hear.

Power The electrical power an amplifier can deliver into a speaker. More power lets you play music louder without harsh distortion, but for most living rooms, a 30-watt amplifier should suffice. For better systems, a higher output is desirable.

Signal-to-noise ratio A measure of the noise generated by a system against the normal signal level. It's usually expressed in decibels, and the higher the number the better: Around 60 db is acceptable.

Wow and flutter Applied to tape decks and turntables, it's a measure of the variations in motor speed above or below the required speed. Wow refers to slow-speed variations; flutter means faster changes. You want the lowest numbers on these. VISION

Alternate channel viewing (or picture-in-picture) A feature that allows the simultaneous viewing of another program in a window on the screen.

Black matrix A picture tube in which the color phosphors are surrounded by black for increased contrast.

HDTV (or ATV) High-definition television, incorporating 1,000 or more horizontal lines of resolution (as compared to the current 525 standard), wide aspect ratio and digital-quality audio -- it's expected on the market sometime this decade. Also called advanced television. Programming compatibility will be an issue when HDTV becomes available.

LCD Liquid crystal display, the stuff of your run-of-the-mill calculator, is now used in video screens, most often in miniature sets. These must be viewed more or less straight on for the image to be seen; tilting the set up or down effectively makes the picture vanish.

MTS Multichannel television sound allows the VCR to record stereo sound off the air from stereo TV broadcasts.

Joe Brown's annual expenditure on CDs and audio-video equipment exceeds the gross national products of many developing countries. For obvious reasons, his editor refused to give him an expense allowance while preparing this story.