You didn't understand what I said. How can we make sure our listening levels are identical to the noise from your hard drive? I could set my amp volume to a really low level, or blast it out on a concert PA system. Both wrong levels.
First off you need to measure noise levels of the HD from a set distance ie 1" measure the noise during seek test, say 79dB with a sound pressure meter. Then record the sound.
Then on our end get a sound pressure meter out and from our position adjust volume on the amp and playback the video clip until the sound pressure meter reads 79dB. That way what we're hearing is close to the levels you have.
For both recording/playback also have to make sure ambiant noise is as low as possible, so no noisy PC/TV on in the background. Close windows to shut out traffic noise.