Description:

"Different DAC chips were used on the Sound Blaster 16, including CT1701, CT1703-T, CT1703-TBS and CT1703-A. The first of these (which is the oldest variant) is rumoured to be the cause of noise on these cards, so if possible, check for a CT1701 or a variant of the CT1703 that is on the card before you buy it. The CT1703-TBS is apparently decent for noise (low) and is also found on the CT2290, AWE32 and AWE64. The CT1703-A is the most recent and quietest, and is found on numerous later SB16 cards up to AWE64 Gold. So in order of preference, get a card with the CT1703-A, then the CT1703-TBS, and avoid cards with either the CT1701 or CT1703-T."

from https://www.dosdays.co.uk/topics/sb16.php