Hart audio have by virtue of their newest release, the right to say they have created the worlds most expensive loudspeakers, ever. This feat was achieved in a way some may consider a bit of a cheat, they simply made the speakers from solid gold. The weight of 50kg of gold, makes each speaker cabinet the holder of the equivalent of 4 and a half Gold bullion bars, of the "good delivery" standard.
As for the technology side of things, we have D&W loudspeakers, 3 sepakers drive units, a super tweeter and the capacity to maximise all modern forms of high end digital formats. The sensitivity range is 97bd 1w@1mtr, an impedence of 5 ohms, and a frequency range of 47 Hz - 37Khz.
At £3.5 million, or $4.7 million, they actually represent a fairly good value purchase regarding the gold value, at current market prices, 100 kilos of gold is worth around £3.3 million, therefore at present they are only asking a premium of £200,000 for the technology, packaging, and branding, and considering this is 100 kilos of gold, the price will only appreciate, as you could always take them to a foundry, melt them down, and sell the gold.