The Irishman Barry Douglas adores opera. Even if a listener did not know that, he might have guessed it from the pianist's performance last night in Meyerhoff Hall of Mozart's Concerto No. 25 in C Major (K. 503) with the Baltimore Symphony Orchestra and conductor Christopher Seaman. Douglas' performance was more than than a matter of lovely tone, sensitive phrasing and an ability to articulate details that did not interfere with a listener's ability to hear the piece whole. These are admirable qualities, but Douglas brought to this piece a capacity to inflect phrases and to create timbres in unpredictable ways that suggested the human voice in either solitary lyricism or public declamation. And though his playing could exhibit ravishing delicacy, he never let the listener forget // that K. 503 is -- along with K. 482 -- the grandest of the composer's works for piano and orchestra. This was playing that was grand without being heavy and that -- particularly in the pianist's own superb cadenzas -- sometimes suggested a Beethovenian spaciousness. But the operatic depends on the dramatic -- on the interplay between different voices -- and the accompaniment that the pianist received from Seaman and the orchestra let him down. Had BSO music director David Zinman been conducting, there would have been more of a genuine collaboration. The repeated chords of the first movement would have had more bite and definition, the interplay between the solo instrument and the winds would have been more detailed, and more flexible pacing would have freed the pianist to play even more spontaneously. In Dukas' "The Sorcerer's Apprentice," which opened the program, the conductor gave a performance that was better, but that could have used more zest and refinement. Seaman's best qualities were in evidence in the fine concluding performance of Mendelssohn's "Reformation" Symphony. Here was the kind of committed, open-hearted musicianship and deeply felt emotion that makes this conductor's work in Elgar and (sometimes) Brahms so memorable. The orchestra played well for him -- its strings smooth, its brasses sonorous and its woodwinds sensitive. The concert will be repeated tonight at 8:15 and Sunday afternoon at 3.