Not Khz, but Mhz (!). 2.8 Mhz for the MR-1, and 5.6 Mhz for it's big brother, the MR-1000. There is a good explanation on Korg's Website here:
http://www.korg.com/mr/Future_Proof_Rec ... lained.pdf
The graphs showing a 20 Khz square wave are particularly interesting. I have observed this myself looking at the output of a 24-Bit / 96Khz AD converter on an oscilloscope. I couldn't believe how distorted the waveform gets as you go up in frequency. Even at 5 Khz, a square wave is not recognizable as such, and by 20K it's indistinguishable from a sine wave, as shown in the graph.
1-Bit processing at 5.6Mhz (or even 2.8 Mhz) represents a huge step forward in quality, even though 24-bit 96K doesn't sound too shabby, despite the apparent waveform distortion.
This looks like a really interesting product, and probably a harbinger of where the industry is headed. Right now, it seems more like an archive format, since there isn't really any workstation software (that I know of) that can process in the 1-bit domain.
If I were in the market for really high quality field recorder, I think I'd try to pony up the 1200 bucks for the MR-1000, with it's higher sample rate, bigger hard drive, built-in mic preamps, and most importantly, the ability to use AA batteries instead of being limited to the internal battery in the MR-1. This should also be an excellent machine for those who like to mix down to an external device for mastering.
