Yeah, Michael; typical speakers are a bit less than 1% efficient at turning electrical energy into acoustical energy. For example, at the usual 1 meter measuring distance an acoustic watt would be at about at a 112dB level. If instead the speaker put out only 102dB(a tenth of an acoustic watt)for 1 watt of electrical power input, that would represent an efficiency of about 10%; if 92dB, about 1%. The rest is primarily lost as heat, as Chris pointed out.
So, on some of those scorchers in Kuala Lumpur you can turn down the volume(or turn up the air conditioning). Incidentally, I was just listening to an excellent Rimsky-Korsakov collection by your home-town band, the Malaysian Philharmonic. Do you have any of their recordings?