The metamorphosis that the Deller Consort has gone through over the past 10 years has left the ensemble relatively unchanged. True, Alfred Deller, the founder and counter-tenor mainstay of the group, has died, but his chair has been ably filled by his son, Mark. He is possessed of a somewhat sweeter voice than his father's and a lot of the same charm and musical sense. There are new sopranos and a tenor, all meticulous singers and sensitive musicians. And, amazingly, baritone Maurice Bevan goes on and on, his voice, if anything, more resonant and more flexible than ever, but still projected with the familiar ease and gentleness.

At the Library of Congress last night, the program grouped madrigals and lute selections from the courts of Henry VIII and Elizabeth, and the Shakespearean and Restoration theaters.

The Consort handles ensemble in the best tradition of the finest string quartets. Its unanimity was as effective in simple pieces like "Pastime With Good Company," attributed to Henry VIII himself, and Jones' "Farewell Dear Love" as it was in Tomkins' sophisticated "Too Much I Late Lamented."

Its otherworldly performance of Pygott's "Quid Petis O Fili" characterized the Tudor Court as vividly as did the rowdy and highly impolite "Hoyda Jolly Rutterkin" by Cornysh.

The humorous dialogues of the Restoration theater, with its ribald coarseness, were done with zest but also with a modicum of restraint.

The Consort puts on few airs, and its affectations are the artistic ones of well-groomed diction, stylized phrasing and delicate balance and intonation. It was a pleasure to have it back in town.