I would consider replacing the reservoirs a fairly random decision - and I fail to see where 'research' would suggest such a thing?.
If you don't understand "the amplifier output stages have blown", perhaps you shouldn't be attempting this repair?. DC coupled amplifiers are like a chain of dominoes, if one device fails it's very likely many more will have failed as well - and it's very easy to cause more damage.
Do you have a schematic you could post?, without that it's difficult to make suggestions - for a start is it an IC amplifier, or a discrete one?.