LAS VEGAS, JAN. 9 -- A tape recorder that lets users play compact disc-quality tapes without abandoning their old cassettes and a black box that brings interactive sound-and-video technology to home TV were among the early gambles demonstrated on the eve of the Consumer Electronics Show, an annual extravaganza of home entertainment gadgets here.

The show officially opens Thursday, but some of the biggest names in consumer electronics were a day early with their bets on what they think Americans will want to buy in coming years. Philips N.V., the Dutch electronics giant, hopes to change the way people listen to music; and Commodore International, the U.S. computer firm, thinks it can marry the TV with the computer to produce a home center for entertainment and education.

With its demonstration of a new audio format, Philips set in motion what is sure to be a lengthy slugfest among equipment manufacturers and record companies hoping to influence the next standard for music listening in the home and car.

Though consumers who already juggle records, tapes and compact discs may be wary of yet another format, manufacturers are counting on the next audio boom to arrive in the form of digital tape recorders. The recorders promise tapes with the crisp sound of CDs, plus the advantage to consumers of being able to digitally record and copy music without losing quality. Home CD systems can copy music only onto lower-quality cassettes, not onto compact discs.

Philips's entry has drawn attention since it was first described in October because it will play existing cassette tapes as well as new digital tapes. The first digital recorders, known as digital audio tape (DAT) recorders and championed by Sony Corp., will play only tapes specially recorded in the DAT format.

DAT recorders have failed to make much of a splash since their U.S. introduction last summer. With prices close to $1,000 and with no more than a few dozen titles available in the format, the recorders may be destined for a limited role.

The Philips system, some industry officials say, may stand a better chance in the mass market because consumers could buy the new recorders without rendering their existing cassette libraries obsolete.

"The transition is virtually painless, whereas the DAT transition is painful," said Russ Solomon, president of Tower Records, an international chain of record stores.

Philips, which pioneered the cassette tape and co-developed the CD, said today it expects to introduce its new system in 1992 at roughly $500.

Tandy Corp. said it will manufacture equipment and tape in the new format, and Philips said it is working with a Japanese firm, believed to be Matsushita Electric Industrial Co.

Far from a certain success, Philips's system faces opposition from the Recording Industry Association of America, the trade group that believes record companies are being deprived of millions of dollars in revenue by consumers who violate copyrights by recording songs onto tapes. After mounting a copyright challenge to DAT, the group was successful in winning a concession from DAT recorder makers in the form of a microchip that allows users to copy a CD, but does not permit a digital copy of that tape copy.

Philips plans to include the same circuitry in its system, but that may not satisfy songwriters or record companies.

Questions about the sound quality of Philips's system also persist. In the process of digital recording, Philips's system encodes only the amount of detail in the music that can be detected by the human ear, while DAT faithfully records everything. Some people who have previewed the system say the differences between it and DAT are minimal.

Just as industry experts are unwilling to say Philips's technology is a sure bet, they're also not sure whether Commodore International's newest introduction will be a winner. But the computer company is putting its money on its so-called CDTV player, a blend of sorts between a Nintendo entertainment center and a personal computer.

The sleek black player looks like a stereo but is a personal computer that hooks up to a television and plays CDs -- either the conventional audio sort or special CDs that include sound plus still pictures and video images. Users of the system guide themselves through pictures, sounds and text in what is being billed as the first "interactive multimedia" system for the home. The system is called "interactive" because users can choose whether they want more detail on a certain topic. CDs announced today for the $999 system, which should be available in March, include those geared toward childhood education, games and leisure activities.

A CD about American history, for example, might contain some text about Martin Luther King Jr. Then, by using a remote control, the user could activate the CD to play the "I Have a Dream" speech. At other points, a portion of the screen would play a full-motion video.

Some industry insiders are doubtful about the machine's prospects. "I didn't get excited, and I didn't see other people getting excited," said Lee Isgur, an analyst with Volpe, Welty & Co. who viewed CDTV at a trade show last fall. "They weren't lined up three deep."