Complex sentence: Clearmountain was said to have been one of the first recording engineers to hang tissue paper over the tweeters of the NS-10 to tame the over-bright treble that would result in mixes that were treble-deficient when replayed on normal domestic hi-fi.
Split into simpler sentences: Clearmountain was said to have been one of the first recording engineers to hang tissue paper over the tweeters of the NS-10 to tame the over-bright treble. Covering the tweeters with tissue paper was said to produce treble-deficient mixes when replayed on normal domestic hi-fi.