some have circuitry to protect against this, but many don't . . . my reason for the inquiry -- how many auction (o.k., eBay) listings have you seen where a "powerseller" / pawnshop says that the poweramp powers up, but they don't know if it works otherwise - and item is sold "as is" with a speaker cable / binding posts connected but no cab - that would be very bad, but what if a poweramp is turned on with nothing attached ... bad ? Thanks.