NY is right that with say a film image there's theoretically no limit to the amount of potential "detail" but there's is a definiite limit to the detail we're interested in. With sound, humans cant hear beyond about 20kHz max. There might be a "universe" of potential information above 20kHz but no one hears it. in any case when it comes to capturing huge bandwidth, digital recording kills analog tape recording. Tape is limited to about ten octaves due to the limitations of the inductive tape heads. If we really want to capture audio information that no one will hear, digital is the better tool.