They move into a room easily, smiling, dispensing witticisms, chuckling, exuding a youthful charisma. Suddenly, effortlessly, they break into song - usually jazz or swing - in tight harmony, patterned after a favorite group, Manhattan Transfer, or perhaps the legendary Four Freshmen.

But they are also unique. Classy. Sure of themselves without being egotistical. They are a sophisticated mixed quartet, and they call themselves Crosstowne.On a particular evening Kathy Davis, Mark Roper, David Stringham and Lisa Lund are performing in front of a blazing fireplace in a private home. They are the entertainment for a party sponsored by a computer software firm. After delivering two jazzy, fast-paced numbers complete with gestures and gentle, clever asides, they own the audience.

CROSSTOWNE CRISSCROSSES the Salt Lake Valley all year 'round and is especially busy during the holidays, singing at house parties, hotel gatherings, a Park City festival here, a Snowbird festival there, the State Fair. Frequently they sing sacred programs at the First Presbyterian Church, in an LDS meetinghouse or at other churches that extend an invitation. They've really enjoyed singing with the University of Utah jazz band.

The quartet has a healthy repertoire of both popular standards and sacred music, and can sing nonstop for two or three hours without repeating themselves. They enjoy doing a full program of sacred music as much as they do swing.

The group rarely plans comedy routines with which to intersperse their singing. They are witty enough and comfortable enough with each other that spontaneous humor takes over when they really connect with the audience.

But they'll probably never get rich. What they care about is the singing itself and their coveted companionship. They are best friends. Davis, who sings alto, initiated the group nine years ago. Davis, who has a degree in music education from the U., had always admired her mother's membership in a quartet and her predilection for arranging her own music.

Roper, a tenor and another founding member, has enjoyed singing from the time he was a child. He went to the U. and Salt Lake Community College, then went into accounting. When Davis asked him if he was interested in singing in a quartet, he didn't have to think twice.

Stringham, the bass, is a computer programmer. He enthusiastically joined the group a little later, after a predecessor bowed out. "My whole family has been performers," says Stringham. "It seemed that my mother wanted us to be the next Osmonds or something. We had so much fun getting together - the seven of us - singing and performing. I played trumpet in elementary school and junior high, then somewhere switched over to voice. I think it was more visual. I could be seen."

Lund, the soprano, is the most recent addition - four years ago. She is the only single member and a "find" - the soprano the group was waiting for. They went through eight other sopranos before they landed her, and now they feel they have staying power. "It took us several years, but now we are where we want to be," says Davis.

Lund has been singing in small groups since she was 5 years old and has taken private voice lessons for six years. She is a junior at the U., majoring in music. The rest consider her a quick study because after her audition she had just three weeks to learn a stack of music before Crosstowne sang at the State Fair and several events in Park City.

She passed the test. Now, says Stringham, tongue firmly planted in his cheek, "there is a requirement that the soprano not marry or go on a mission."

Their accompanist, Kelly DeHaan, occasionally doubles as a singer. He studies music education at the U., gives voice and piano lessons and sings. He has been with the group three years and was brought in by Lund. While Kelly is an integral part of the group, he cannot accompany in a home with no piano. In those cases, the versatile Crosstowners make an easy transition to a cappella.

Their style of dress was carefully and artfully conceived. They sought the advice of a U. music teacher, Shannon Roberts. "We said, `This is our sound - what do we need to look like?' " Roper says. Roberts' response was that they should cultivate separate looks that go well together. They should go for a classy look, but not match exactly.

So, for formal gatherings the men wear double-breasted jackets and T-shirts in complementary colors while the women go for casual chic, such as black, dressy, one-piece pantsuits that look great but guard their individuality. For the men, beards come and go. Currently, both sport trim, short beards, but Stringham does not always wear one.

Coincidentally they present an esthetic physical appearance as well, with all four standing about the same height. That wasn't planned, they say, although they are glad there isn't one member who is outlandishly tall or one who is notably tiny.

More important than appearance, they blend beautifully, with no voice ever overpowering the others. Each member does periodic solos, depending on the needs of the music, and whichever voice fits it the best.

For the first few years, any income they earned mostly paid for incidentals. While they do have a standard fee now for their performances, it was a long time coming. Stringham remembers their first Christmas season singing together, when they made only $35, and the money stunned them. "It was so cool - we divided it up, and I got seven bucks!"

Davis says, "When people started to offer us money, we thought, `I guess we should ASK for that much!' " During the holidays, at least, they make a reasonable side income.

The four are as much performers as they are singers.

Only Roper claims a tendency to shyness, and all have spent time as thespians and love to appear in front of people. In fact, they thrive on the chemistry established with an audience and tend to improvise even their own arrangements. So far they have not cut their own album, although that is just around the corner.

Practices each week are hard, down-to-earth work sessions, usually lasting four hours. The Cross-towners enjoy each other and talk and laugh a lot, but they also spend a lot of time singing and working to improve. The four enjoy the time together, not only because of the blend of personalities, but because each is good in singing the appropriate part, and no one has to worry about anyone else.

All of them like their jobs and their schoolwork, but it is singing that they enjoy most. They plan to stay together for as long as they possibly can. Lund says, "I just want to keep getting better. I just want to keep doing it. It is a very big hobby that we take a little more seriously than a lot of people take their hobbies."

Adds Roper, "We have our jobs, but this is our lives. It would really be boring NOT to do it."

All quartets have problems, of course. They have their occasional little squabbles, which are soon forgotten. The group agrees that "Kathy Standard Time" is about 20 minutes past the agreed upon beginning hour - but that applies to practices, not performances. The group accepts Davis' propensity for tardiness so well that they don't even consider her late unless she is later than 20 minutes.

All consummate musicians, each plays alternate roles arranging Crosstowne's music, and Lund is writing original songs for them to sing. They sing a lot of old standards, and they often take a more recent song and give it a jazz arrangement. Most of all, they want their arrangements to be "something different - something no one else has." The members of Crosstowne believe that if people like a wide range of music, "they'll probably like what we do."

Count on it.

Crosstowne's first spring concert will begin at 7:30 p.m. Saturday, May 4, at the First Presbyterian Church, South Temple and C streets. The selections will be mostly secular, consisting of older jazz, newer pop and a few gospel numbers. Admission is free.