It's extremely doubtful it's a batch-oriented problem, since Magnis (like all of our products) are tested extensively on automated test equipment (ATE) and also with a final listening test, after burn-in. If there was a problem with many units, we would have caught it, as we have caught other production problems that never made it to shipping. Bottom line, we live in an RF-saturated, noise-contaminated power line environment, and no product can offer complete immunity from that. See this post for some (rambling) detail: http://www.head-fi.org/t/640783/schiit-magni-headphone-amplifier/1815#post_9851471
What you don't hear from are the now nearly 8k Magni owners who aren't having problems with their amps.
Thanks for clarifying that. I guess I could get used to living with the issues. Anyways I can hear the scratching and humming only when there is no music playing(quite natural). Who wants to just plug headphones and not listen to any music