I know someone who bought, for his own kitchen, a stove intended for the restaurant trade, simply because it enhances his enjoyment of cooking. Another friend, a motoring enthusiast, has equipped his garage with a brace of tools, including a hydraulic lift, that would be the envy of some humbler repair shops. Yet another friend indulges her enthusiasm for ceramics with a potter's wheel and kiln that one might find in a well-endowed art school. Among the most serious consumers, it seems, the watchword is professional; odd, then, that professional-quality monitors don't account for an even bigger chunk of the domestic loudspeaker market.