MAX77501 could support up to 25MHz SPI frequency, so 16MHz is ok. The waveform sample rate is independent to SPI frequency.
MAX77501
Recommended for New Designs
The MAX77501 is a high-efficiency controller driver for piezo haptic actuators and is optimized for driving up to 2µF piezo elements. It can generate...
Datasheet
MAX77501 on Analog.com
MAX77501 could support up to 25MHz SPI frequency, so 16MHz is ok. The waveform sample rate is independent to SPI frequency.