Like Frank said, the number of fuses depends on equipment manufacturer/designer. Most equipment will have one fuse on the A/C mains input.
Some designers will load their equipment with fuses both before and after the transformer. Example would be Parasound JC1 which has 7 fuses that directly affect the audio path and another 3 that do not affect audio (standby and trigger/turn-on circuits). Even with this, just changing the primary A/C mains fuse on the back panel will yield improvements/changes. Marantz is another company where you see a lot of fuses inside their equipment.
Some equipment may appear to not have a fuse and uses a circuit breaker instead, but in actuality still uses a standard fuse internally. Example would be the Bryston 7b monoblocks.
Some equipment does not use a fuse at all and only uses a circuit breaker. Example is the latest Emotiva Gen 3 amps.