AD736 input amplitude for 32kHZ
Too low for what?

If the you read the third line of the first paragraph of the data sheet, it says 'use an input attenuator for larger input voltages' (or words to that effect).

It's not too low for a signal correctly scaled into the 200mV range by an input attenuator!

You can put any voltage between supply and ground into any pin without damage (see the absolute maximums table), but you won't be getting the specified conversion accuracy under those conditions.

If you carry on reading further into the datasheet (it never hurts to R all of the TFM before asking a question) you find that you can apply 300mV rms through the low impedance input with low voltage rails, and up to 1V rms when you use power rails of at least +/-5V. The peak transient is +/- 11V on the low impedance input when you use +/- 16.5V rails. Figure 4 page 7 has a nice graph of maximum input level versus supply voltage, and figure 6 gives error versus signal level.

If you are actually going to use the thing in anger, you need to pore over all of the 'additional error versus ...' graphs to see whether it will meet your accuracy needs.