You think you don't need stereo television? Oh yes you do need stereo television. If you had stereo television, your life would be a picnic, a romp, a waltz in swingtime, a laff riot, a Springsteen concert, a tableau vivant, a date with Judy, a Sunday in the country, a night on Bald Mountain, a trip to the moon on gossamer wings, and so on and so forth.

After all, do we dream in mono? No, we dream in stereo (What is a hamburger -- chopped ham? No, it's chopped steak, but that's another matter). Additionally, some of us dream in Technicolor, some of us dream in Color by Deluxe. Refined people dream in Beta and the riffraff dream in VHS. And so forth and so on. The point is that stereo television has arrived.

It arrived for good on Tuesday, July 23. Indeed, when the history of stereophonic television is written (and the history of everything gets written eventually; writers are like that) this will be the date that will live in 'famy. NOTHING WOULD EVER BE THE SAME. 'Twas the night of the first nationwide stereophonic telecast of "The Tonight Show Starring Johnny Carson."

How thrilling it was to be in one's living room and witness this breakthrough. And you didn't have to wait long, once those long, long years of monaural waiting were over. The show was in stereo from the word "from" (Ed McMahon: "From Hollywood, it's the . . . "). Doc Severinsen's band playing "dah dah dah dahhhh dah" was clearly in stereo, horns on the left and, er, other horns on the right. But the payoff was the monologue, always the highlight of the show.

Now, a man telling jokes to an audience doesn't sound as if it would be much enhanced by stereophonic sound. Wrong, frequency modulation breath! Because in stereo, you not only hear Johnny in the center and the audience all around -- you hear Ed laughing on the left and Doc laughing on the right! And if they don't laugh, they don't get paid! It's as if you were really there, which is fine on the condition that really there is where you would like to be.

It's like having Johnny and Ed and Doc (they do stand to the audience's left and right, respectively, in the studio) right there in the house, albeit only about eight inches high each, of course. The sense of ambiance is enormously heightened, so much so that not only is the laughter more infectious, but the occasional absence of laughter danker and more profound.

Stereo TV is going to change the way we look at television as well as the way we listen to it. Why, it's the single most exciting technological breakthrough in American consumerism since the introduction of Double-Stuff Oreos.

It's Double-Stuff Television -- two, two, two sound tracks in one. Or actually two sound tracks in two, if the dang thing is working right. True, there are hardly any stereo TV sets in use right now, but prosperity is right around the corner. Mondo Mono will give way to Mondo Stereo. It's only a matter of time.

No, it's also a matter of money. It will cost networks and stations from thousands to millions of dollars to switch to stereo, which really is not much considering the tons of dough they all make. About 100 U.S. TV stations have gone stereo so far including, in this neck of the woods, Channel 4 (WRC-TV, the NBC affiliate), Channel 20 (which aired "Live Aid" in it), Channel 22 (a Maryland public TV station) and Channel 13 (the ABC affiliate in Baltimore). Although these stations send out a two-channel audio signal, most of their programming is still produced in mono, so even stereo set owners hear only double mono most of the time.

Closer still to home, stereo TV will cost consumers who want to upgrade their living room listening posts. People who are now buying a new TV and figure they may as well get it with stereo will find that the stereo feature adds about $100 to the cost of the set.

Some sets made by Sony and Zenith in the past few years are "stereo-ready." That means that their owners can purchase a $180 decoder that will enable the sets to receive the stereo audio signal and channel it into a couple of speakers. Manufacturers like RCA (which owns NBC) restrict stereo to their top-of-the-line models and don't have any convertibles and, hence, no converters.

Some newer models of Beta Hi-Fi VCRs can pick up TV stereo signals and need only be hooked up to a home sound system for playback in stereo. The crudely inferior VHS system (yech, pooey), which has never been able to equal Beta Hi-Fi in sound quality or economy (the cheapest VHS Hi-Fi machine costs $300 more than the cheapest Beta Hi-Fi) is not ready for the stereo age. Only VHS machines in the $1,000 price range can pick up stereo TV, whereas Sony makes a $650 Beta model that does.

Now there are a few more hitches.

First of all, hardly any TV programs are produced in stereo.

Even if a station is transmitting a stereo signal, what a viewer is probably getting is synthesized stereo, or mono-a-mono. But that is changing. NBC has announced that at least nine of its shows will be in true stereo as of this fall, including "The Cosby Show" and new arrivals "The Golden Girls" and "227." A limited-run summer series, "Motown Revue Starring Smokey Robinson," which premieres Friday, Aug. 9, will be in stereo, as will be this year's Miss America pageant, on NBC Sept. 14.

Incredibly enough, parsimonious NBC has yet to decide whether "Miami Vice," heavily reliant on a rock tune track, will be stereocast, though "Punky Brewster" definitely will be. "Friday Night Videos" has been in stereo since July 19.

Sports events are said to be particularly ripe for stereofication. Something about the crowd noises. Big wow. NBC broadcast the All-Star Game in stereo July 16. The Atlanta "SuperStation" is airing some of those dreadful Braves games in stereo, and selected events on the ESPN sports cable network are in stereo, too. HBO has been promising to go stereo for years, but it's too busy watching its market share diminish. PBS viewers have long enjoyed stereo simulcasts of musical events; with TV stereo, you don't need the "simul" -- the separate FM radio. It all comes with the TV signal.

And what of the other networks? A spokesman for ABC, questioned on the subject of stereofication yesterday, said, "You know, I was just asking somebody, 'Are we going to do something about this or aren't we going to do something about this?' And the answer I got was a blank stare."

George Schweitzer, CBS vice president, said, "We see stereo as evolutionary, not revolutionary. We are slowly but surely going to convert our facilities, but we have no target date. We're not jumping in with both feet. It's going to cost us a lot of money." They're such wild and crazy guys at CBS. Schweitzer said that NBC has several shows with high musical content, but CBS does not and thus feels a weaker stereo imperative. "We have a schedule that is 95 percent dialogue," Schweitzer said. "Will stereo help '60 Minutes'? I don't think so."

Dutifully, earnestly and because he was bored with everything else, your obedient correspondent tuned in for the first stereo night of not only Johnny but the show that follows his on NBC, "Late Night With David Letterman." Just think, the beginning of the birth of the end of an era, but not quite. It was not like being in Paris when Lindy landed. But it was like being at home in 1953 and seeing Arthur Godfrey tell Julius LaRosa he was sacked.

Carson never mentioned or did jokes about stereo, but his show was a veritable symphonie stereophonique compared to David Letterman's. Although Letterman joshed and giggled about being in stereo, his show was stereo in name only. Paul Shaffer's band was not in stereo. Dave's amazing stereo sound effects were not in stereo. The only thing that was really in stereo was the audience.

There was one other stereophonic touch that first night. When announcer Bill Wendell read the regular nightly plug for the New York hotel that puts up Letterman's guests, he was heard on the left channel only. Oh, the wonder of it all! How did we get along without it???

"My face is beet red," confessed David Letterman's producer, Barry Sand, the next day when confronted with the grim reality of the Letterman hoax. "You've caught me with my speakers down. I certainly owe an apology to those eight stereo set users who are outraged by the sham." Sand said NBC technicians would work nonstop on the problem until lunch break and that eventually the program would be true to its labeling.

In the meantime, Letterman continued making sport of the development. When a joke would bomb and the studio audience would groan, he would turn to them and say, "But it's in stereo!" His joke wasn't, but their groaning was.

The real effects of stereo won't be felt, however, until Madison Avenue has fully tooled up for this godsend. Those taunting teases the Doublemint twins can come back and each get their own speaker. The snap, crackle and pop of Rice Krispies will sound like World War III. The Tidy Bowl man will adapt to the changing environment by -- well, it's too horrible to contemplate. Besides, I might be able to get a whole other column out of this.

Television engineers will have the most fun of anyone, probably. Now after nearly four decades of making the commercials louder than the programs in mere mono, they can make the commercials louder than the programs in sheer stereo. The only conceivable improvement beyond this would be that on "Reach out and touch someone," somebody would actually reach out of the TV set and touch you. Science will find a way.