There is no such thing as a hifi or pro audio amplfier, an amp is an amp. at the electrical level.
to prove this, I would ask someone who disputes to tell me exactly what design features constitutes a hifi circuit, perhaps even audiophile, and demonstrates it gives better sound.
Its marketing again.
Though amplfiers for the pro audio market do tend to be more ruggedly built in general, and as said, sevicable.
And hifi amps smaller and perhaps in the near past, lighter, with less watts maybe.
Traditionally, tone controls may have been on hifi amps ,esp jap ones, whearas in the pro arena, eq. would be used.
Benefits of pro:
power
ruggedness
backup support
competitive pricing with each other
better value by far than hifi
manufacturers that aren't totally paranoid about others seeing their circuits.
cons:
looks
weight perhaps
psychological...not hifi?
are we being ripped off...yes as with lots of things...1000 watts? hifi mega bucks, pro audio, yes sir, £1500 perhaps.