His mother, Lavinia McPhee (née Carhart) was originally from New Jersey and settled in Montréal after marrying Alexander.

In 1942, he arranged Britten's Variations on a Theme of Frank Bridge, a work for string orchestra, for two pianos, to be used for Lew Christensen's ballet Jinx.

[6] McPhee was responsible for introducing Britten to the Balinese music that influenced such works by the British composer as The Prince of the Pagodas, Curlew River, and Death in Venice.

[12] American composer Evan Ziporyn wrote an opera about McPhee's life, titled A House in Bali.

In 2017, an album Peter Pears: Balinese Ceremonial Music, performed Thomas Bartlett & Nico Muhly and partly based on McPhee's transcriptions, was released on the Nonesuch/Warners label.

Its title translates as "collection of percussion instruments", and it combines Balinese and traditional Western musical elements.

It is scored for Western orchestra but, in McPhee's description, the core of the ensemble is a "'nuclear gamelan' composed of two pianos, celesta, xylophone, marimba, and glockenspiel," giving it a percussive balance of sound.