Transforming original quadrophonic tapes into high resolution multichannel mixes in SACD Surround Sound requires a very accurate listening environment, says Stephen Marsh, owner of Marsh Mastering in Los Angeles. “With these old tapes, it’s like listening through a time machine so it is vital that I can hear every nuance of the original sound.”

Luckily for Stephen, he has Bryston-powered PMC IB1S main monitors and OB1 surrounds in his mastering room, plus a PMC CB6 centre speaker that is added as and when it is needed. “The PMC monitors have proved invaluable because they allow me to understand exactly what I'm hearing and I can therefore make quick, effective decisions that are both musically appropriate and technically sound,” he says.

Stephen’s mastering credits include albums by Bob Dylan, James Taylor, America, Yes, Nat King Cole, Eric Clapton, Neil Diamond, Crosby Stills & Nash, Heart, Bad Company, Dio, Bread, Phil Collins, Janis Joplin, Blood, Sweat & Tears, Earth Wind & Fire, Joe Walsh and Donny Hathaway. He is also a first-call engineer for film, television and game composers with a long list of credits to his name.