Glad you found the problem. Unfortunatly I have no experience with HOLM, so I can't help figure out how to fix it.

I noticed your card has stereo mini connectors, which brings back some nightmares I had long ago with an SB Extigy with stereo jacks. The common-to-both-channels neutral pin wasn't grounded, nor was the output neutral common to the input neutral. The details of the problems that caused were too many problems ago for me to remember, all I remember was it was unusable for some testing purposes, so I gave it to a friend's kid to play MP3s through. Might not be a problem with yours, but if it keeps anyone from using an Extigy for measurements, the time it took to type was worth it. (FWIW, the clue that led me to the solution was an unexplainably high degree of stereo crosstalk noted by RMAA).

Another past problem I've had that may only be good for general info...

...Any audio apps on your PC may interfere with your measurement app. Some media players can be very controlling when it comes to your sound card settings. Any add-ins you might have like DFX etc might run on anything sent to your card. Took me several hours to figure out a reverb module I had as an audio addin was causing the crap readings I got. I thought that would only run when I told it to, but that wasn't the case. Had to uninstall it.

While my current setup was close to plug-n-test, I've never had a 100% plug-n-test experience. Oh, sure I could run sweeps, but they weren't right until I fixed whatever it took to get all my cal routines and benchmarking to satisfaction.