At the rate it's going, Stephen Sondheim's "Sweeney Todd" is becoming the incredible shrinking musical. Its now legendary original production, directed by Hal Prince, was distinguished by its massive scope and extravagant production values. Years later, a chamber-sized Broadway revival received wide critical acclaim. Now it returns again in this London import, so further reduced that it is largely bereft of scenery and even an orchestra. What's next, shadow puppets?

The production, directed by John Doyle and first seen at England's tiny Watermill Theatre, is a drastic reimagining that, depending on your point of view, either enhances or diminishes the brilliance of Sondheim's classic work about a murderous barber whose victims wind up as the primary ingredient in his cohort Mrs. Lovett's meat pies.

It is performed by a 10-member cast that also doubles as the onstage orchestra. Thus, Michael Cerveris, in the title role, whips out a guitar for one number, while his co-star, Patti LuPone, blows merrily away on a tuba. The supporting actors also play a variety of instruments, including accordion, keyboard, cello and clarinet.

The results emphasize the characterizations and story line as well as the brilliance of the composer's convoluted lyrics. But it necessarily diminishes the Grand Guignol atmosphere of the piece and its musical impact. The score, arguably Sondheim's best, just doesn't have the same force emanating from this ragtag collection of players.

Although the minimalist aesthetics of the production might have been defensible if presented in a highly intimate space, on Broadway, even in the relatively intimate Eugene O'Neill Theatre, it mainly comes across as wan.

Nonetheless, it's still "Sweeney Todd" and thus remains a compelling musical theater experience. Cerveris and LuPone, two performers not previously known for underplaying, deliver highly effective and restrained performances in the lead roles, even if the former, sporting a bald pate and dark leather jacket, more closely resembles an aging biker than a Victorian-era barber.

Of the supporting players, Mark Jacoby makes Judge Turpin a more interestingly sympathetic figure than usual, Manoel Felciano is superb as the young Tobias, and Lauren Molina, who also plays a mean cello, does well by Johanna.

Doyle certainly has staged the piece in an imaginative fashion, providing clever touches like having the actors don bloodstained smocks when their characters meet their violent ends. But ultimately, the staging seems more intent on calling attention to itself rather than the material, with the result that one comes away more attuned to the mechanics of the production than the brilliance of the piece.