There's really no other way of saying it: these headphones cost £1,099. Yes, one thousand and ninety nine British pounds. The equivalent of US$1,838 and AU$1,957.It's a truly staggering amount of money, enough to buy you 92 pairs of Apple EarPods; 33 iPod shuffles; Or, the metaphysical concept of shame.But suspend your disbelief for just a few minutes and come with me on a journey through the PM-1's credentials and maybe, just maybe, you'll get to the end of this review in the belief that they're worth the cash.Oppo, of course, is better known for its kick-ass Blu-ray players and more recently its Android smartphones than high-end ultra-headphones. But actually, it's not the only reference-grade headphone manufacturer operating out of China - HiFiMAN is also largely based there.