It isn't enough these days to have a set of stereo speakers on each floor of a house. For the ultimate in at-home entertainment, home buyers now can get an acoustical canopy for the bathroom. It plays FM music, opera, country-and-western, or anything else programmed into a stereo system in time for a sing-along in the shower.

The only problem, according to the home builders who are beginning to offer such new gadgetry for the house, is that tough building codes in some jurisdictions forbid installation of any electrical outlets within 10 feet of the bathtub.

"It's a shame," said William Crowell, a Montgomery County builder who specializes in elegant homes for the rich and famous. "We can't put in the pillow massage in the bathtub, either, for the same reason."

Crowell's firm, Crowell and Baker, is building a 6,000-square-foot mansion in Potomac with the latest in electronic innovations, from an in-home computer system that would make most office managers green with envy, to a security system that can be programmed to distinguish between a burglar and the family dog.

"It's for a person who loves gadgets; and who doesn't, these days?" said Audrie Gue, Crowell and Baker's real estate agent. "It's the house of the 1990s, but we're building it today."

If all the systems proposed for Crowell and Baker's self-described "smart house" actually were installed, the cost would be an extra $80,000, Crowell said. Instead, "representative" components, which can be upgraded by the buyer, will be built into the home in the Falconhurst development off River Road, he said. The house is expected to go on the market later this year at a price of about $1.3 million.

While such a complex system is more than the average homeowner needs, high-tech innovations also are being introduced at the lower end of the price scale. Some of these gadgets were exhibited at a building trade show at the D.C. Armory this week.

Leviton Manufacturing Co. is marketing a Home Control System that enables residents to program electrical appliances so that the television, lights, radio and coffee maker can be switched on from the driveway; to dim lights throughout the house from any location; or even to program the aquarium to keep the water warm while the owners are away. The system costs $350 for a standard three-bedroom colonial and requires no new wiring.

Other innovations hitting the market include windows with a protective glaze that can keep drapes and rugs from fading by blocking ultraviolet light. For sun-worshippers, home "tanning beds" are available for about $4,000. Wolff System/SCA has a model that takes up only 32 square feet of space and uses only as much electricity as three hair dryers would during the time it takes to dry hair.

General Electric Co. is offering a refrigerator with a built-in refreshment bar that allows children to get a glass of milk, or grab a can of soda, without opening the refrigerator door. The bar folds down, exposing one of the door shelves and activating a device that cuts cooling loss through the open compartment. The refrigerator retails for about $1,800. GE also is offering a lighter, portable microwave oven, weighing about 45 pounds, that easily can be transported to a vacation home.

Despite the lack of an acoustical canopy and pillow massage in Crowell's house, the master bathroom -- actually a bathroom suite of toilet nooks, tub and shower, dressing rooms and closets -- still promises to be a high-tech heaven for its future owner. It will have a computerized panel to control the speaker-phone system, nine water jets and a facial mist, and controls that allow the owners to turn on the outdoor lights from the depths of the walk-in closet if they think they hear a prowler.

The house will be wired for a computer and phone system that will permit residents to turn on almost anything electrical from nearly anywhere on the property -- even from a car telephone -- handy, for example, if the owner wants to start the microwave oven on the way home from National Airport. The only problem with sending commands to the house via the car phone is that each message generates a phone charge.

To save pennies, then, Crowell and Baker plan to install a gate and garage-door opener that do not use the car phone.

The key-less lock system, however, is a bit more expensive . It emits a constant signal that permits the door to be opened only if someone passes a programmed card in front of the beam. The system is equipped with up to 1,200 different programmable cards, and each card can be set so that the door will open only if -- and when -- the code on the card says it should.

For example, Crowell said, a maid could be given a card that would let her enter the home between 10 a.m. and 2 p.m. But if she -- or anyone else -- tried to use it to enter the house around midnight, the door would not open.

Another major advantage of the key-less lock system is that the owner would not have to take the card out of a purse or wallet. He or she simply would have to wave the purse or wallet in the direction of the sensor and enter -- if the card were programmed to open that door at that time.

The cards also can be programmed to trigger the security system if someone is using the wrong card. If programmed to capacity, the entire key-less lock system would cost $10,000, but Crowell said his Potomac house could get by with just part of the total system.

Crowell said that security is of particular concern to wealthy homeowners. As a result, he said the house will have a system that could be expanded to include gadgets such as a sensor beam that scans the yard to sight anything that moves and is taller than four feet. Such a device would allow the owner to let a dog out at night for a run without tripping the alarm system.

Sensors also will be installed in the front driveway to alert the owner to approaching automobiles.

And the future owner has the option of installing a closed-circuit television system with hidden interior and exterior cameras, like those found in drug stores; a viewer could watch the comings and goings by using a hand-held remote-control unit.

Crowell said that much of the new gadgetry being built into the smart house was developed for commercial customers, including the integrated wiring system for phones and computers.