Some bassists use separate preamplifier/power amplifier setups, where one or more preamplifiers drive one or more power amplifiers. In the latter example, a bass player can use a bass-specific power amplifier or use a sound reinforcement system power amp.
Bass players sometimes use separate preamplifiers and power amplifiers; in certain setups, a player might employ a dedicated bass-specific power amplifier or leverage a sound reinforcement system's power amp.