Some instruments, once you’ve glimpsed them, stay with you. I’ll never forget my brief encounter with the emormous, room-filling RCA Mark II synthesizer, the first of its kind, built in the 1950s and bursting with period charisma, thanks to its towering stacks of vacuum-tube components and endless rows of knobs and dials. Its aura was so redolent of the early-Cold War era, it seemed that if composers like Milton Babbitt and Vladimir Ussachevsky had not kept it so busy, then maybe, just maybe, we might have beaten the Soviets into space.