A problem with testing for HD621 improvement is that the test has more than one variable. In addition to the HD621 as one variable you also have the interface as a second variable. The test with the HD621 requires the HDMI interface whereas the test without the HD621 requires the S/PDIF.
Axle, just what I want to test. Is the HDMI output with HD621 improved over the SPDIF direct into the processor? Most here have said it will be, so I suppose I'd better bring my check book. Hope Steve's (dealer) not reading this.