CDs are encoded at a quality of 16-bit, 44.1khz. However, professional audio is typically recorded at higher bit-rates and sample-rates.

In this video I show where in Logic you can change these settings.

Most humans can't hear frequencies above 20khz (nor below 20hz), however, there is an argument that the higher frequences still matter because of harmonics. In any case, it's a good idea to record at a higher quality even though you will mix down to 16-bit and either 44.1 or 48khz.

Why? Because then you're waiting until the last minute to "round your numbers."

Imagine you're measuring a series of lines and you're going to add the length together, but at the end of the process you're going to want to just report it to the nearest inch.

You could (1) round the numbers after every time you do an addition or (2) wait until the end to round your numbers.

Which will be the most accurate result? (2) of course.

Recording above cd quality is like waiting until the very last moment to round your numbers.