I've had my Colorfly C4 for 10 days now and I am impressed.  I do not own (but have used) an HM801 so I can not give an in depth comparison of the two.  I will say that the Colorfly C4 is all that I hoped it would be.  I've had to recode some of my highest quality 24/96 Flac to 24/192 .wav...