Digitizing an analog tape recording wouldn't change its sound quality. Additionally, anything recorded onto a compact cassette or microcassette (especially by an early 90s answering machine) wouldn't sound anything like the old Butcher recordings do. There would be no high frequency components (audio tapes max out around 17kHz - the maximum audible frequency is around 20kHz) and there would be a lot of noise. Digitizing the recording wouldn't change that. Maybe digital signal processing could make the Butcher's voice sound less like background noise, but Rossi's recording that he plays for Reid should not have sounded anywhere near as clear is it did.