sentences:  In an ideal ADC, where the quantization error is uniformly distributed between formula_1 least significant bit (LSB) and where the signal has a uniform distribution covering all quantization levels, the signal-to-quantization-noise ratio (SQNR) can be calculated from
  
  where Q is the number of quantization bits and the result is measured in decibels (dB).Therefore 16-bit digital audio found on CDs has a theoretical maximum SNR of 96 dB and professional 24-bit digital audio tops out as 144 dB., digital audio converter technology is limited to a SNR of about 123 dB (effectively 21-bits) because of real-world limitations in integrated circuit design.