At half past six the results of my latest foray into consumerism are brought round to the house. A Sony Walkman II - an amazing miniaturized stereo set, with thin, light headphones and a cassette-sized playing machine. If they can make such sound reproduction quality so small now, what of the next ten years? A button perhaps? A pill you swallow which recreates the 8-track wonders of Beethoven's Ninth from inside your body?