A friend uses the Sony PCM D100 and it does sound amazing, but its £600…but you may be able to shop around. I think @Richard.Dane has a couple and may have some better suggestions in your budget range.
The PCM-D100 is very nice, and don’t dismiss the earlier PCM-D50 either. I’ve had both and still have the D100. the D100 will record at 24/192 and also in DSD. As a stand alone stereo recorder with in-built Mics they are superb. They also have line in and line out with good low noise stages. I sold my mint D50 for around £300 a year or so ago, so that gives you an idea. Only drawback is the use of Memory Sticks on the D50. the later D100 adds SD card capability.
Thanks guys. Just had a look at that Sony D100 and it does look pretty amazing, and the ability to record in DSD is a real bonus. I might have to find a way of scraping together the extra £200, it does seem worth the extra.