In this embarrassment of riches that is the New York classical music scene, it is often difficult to decide which concerts to attend. But when one program offers two of my own top 10 pieces of instrumental music that are hardly ever performed together, the choice is obvious. For its opening night recital Wednesday evening, the Lyric Chamber Music Society paired two pinnacles of the Mozart oeuvre, one multifaceted and one sublime.

The Clarinet Quintet and the Concerto for Clarinet and Orchestra are comprised of sonorous combinations much too delicious to translate into the pathetically inadequate words of a critic. For a listener, they are both works of heavenly transportation. It may be Wolfgang’s birthday, but at this program, I could easily think that it was mine.

But first, a rarity. Mozart worked on a second Quintet for Clarinet and Strings that exists today only as a fragment. Soloist Igor Begelman and a quartet consisting of Yulia Ziskel and Yuri Namkung, violins; Mark Holloway, viola; and Dmitri Kouzov, cello, ran through a reconstruction of its only surviving movement by Mozart scholar Robert Levin. This was playful music but in a nostalgic frame of mind. Mr. Begelman performed the work using a standard B flat clarinet.

Well, of course he did. What was he supposed to use, a tuba? I mention this only because for the remainder of the evening, Mr. Begelman abandoned his regular instrument in favor of a modern hybrid meant to replicate a unique instrument of Mozart’s time.Between their publication in the very early days of the 19th century and approximately 1970, both the quintet and the concerto were performed almost exclusively on a clarinet tuned in A. These pieces, however, were written during the era of the basset horn and it was this instrument that the composer first envisioned as the featured performer. Mozart’s clarinetist friend Anton Stadler had an oddity custom-made to present these works and it was this design employed by Mr. Begelman.

Christened the “basset clarinet,” this longer and heftier woodwind looks like a clarinet on steroids. It allows for four additional notes at the bottom of the range, and is immediately earcatching.This was a solid performance, although certainly showed room for improvement, and was well worth the price of admission just to experience the difference between instruments.

It would be quite a stretch to describe Mr. Begelman’s tone as beautiful, but it is confidently robust and vigorous. Perhaps it was the exotic nature of his instrument, but, although he intoned with near note perfect accuracy, he never made the thing sing.The backup strings were competent, but there was little sense of proper blending, the aggregate sound often a bit thin. Mozart’s genius in the quintet is his ability to develop sounds organically.In a superb performance, a violin passage will be taken up seamlessly by the clarinet, sounding for all the world like the same instrument in a different register. This type of subtle tone painting, refined even further by Brahms in his own reverential Clarinet Quintet, was simply not on display this evening.

Rather remarkably, the 18-member orchestra produced an aggregate sound quite dazzling for that little room. Conductorless, they provided a solid foundation for Mr. Begelman in the concerto.There was some occasional shrillness in the violins and a couple of clams from the horns, but overall this was yeoman-like music-making.

The concerto is light-years away from the quintet. Mozart explores a number of divergent moods and it takes a true poet to communicate this music properly. Mr. Begelman, who, to be fair, did quite a bit of the heavy lifting this night, was impressive as a technician, but was not able to mold his voice into the type of protean personality necessary for such a tour de force. He was neither devout in the Adagio nor jocund in the Rondo. His motto seemed to be “safe at any speed.”

Although this young man is obviously a remarkably accurate player, he is also just as obviously a product of the American conservatory system. His approach is overly cautious and always gingerly, as if hitting a wrong note were punishable by death. As a result, his music does not breathe very well, committing through its cautiousness the much more egregious sin of tedium. I couldn’t help but wonder whether he might have grown into a more proficient interpretive artist had he stayed home to study in his native Kiev.