Standard of reference used when expressing levels.
"Oh my gosh! Just got my CD's today and I can't believe the quality of them! It brought tears to my eyes to hear a recording that I haven't heard in over 30 years. You did a fantastic job on tapes that were old and haven't been played in a long time. The sound and even the wording on the CD's is amazing!!! Keep up the great work and I would ..."