A standard level, such as O VU, + 4 dBm, O dBV, to which other levels may be compared.
"RECEIVED THE CD. TODAY AND AS USUAL YOUR WORK IS REMARKABLE. I COULDN'T BELIEVE THE IMPROVEMENT IN THE SOUND. IT WAS WELL WORTH THE ADDITONAL MONEY. I AGREE, CONSIDERING WHAT WE STARTED WITH ITS AMAZING. THANKS AGAIN FOR ALL YOUR HARD WORK AND PATIENCE. HAVE A GOOD WEEKEND. SINCERELY,"