DVORAK:CELLO CONCERTO. REICHA: CELLO CONCERTO IN A. Emanuel Feuermann, cello; National Orchestral Assn. conducted by Leon Barzin. INSYNC C4162 (mono) (cassette only). BLOCH: "SCHELOMO." DVORAK: "SILENT WOODS," RONDO IN G MINOR. D'ALBERT: CELLO CONCERTO. Feuermann, cello; National Orchestral Assn. conducted by Barzin. INSYNC C4163 (mono) (cassette only). Like a treasure both lost and forgotten, these glorious performances serve as a glowing memorial to the Austrian cellist, who died prematurely at 42, leaving only a meager recorded legacy. Drawn from 1940-41 Carnegie Hall airchecks, the material reveals Feuermann as an inveterate romantic, imbued with the airiest of singing tones, incisive attacks and consummate taste. The Dvorak Concerto carries lyricism and buoyancy to an inspired level, and one will find illuminations, too, in the formulaic Reicha and the eclectic but fascinating D'Albert. Barzin lends solid support, and INSYNC's "real time" digital remastering of the acetate originals is a small miracle of technology.