Quoted from P2K:... The board works OK but I would like to see if the sounds I hear are the original sounds or aged sounds due to old components.
Replacing the capacitors is not a bad idea (and mainly for thoses used to filter the power source), but I think that there should be no 'reference' sound even when the board was new.
As far as I see, on this one, the sounds are generated by oscillators made with transistors, caps and resistors. But, did you notice that some resistors have a silver ring as tolerance indication... meaning +/- 10 % ? It is therefore manufactured with components with inaccurate values, and the frequencies generated would vary greatly from one board to another .
For this kind of soundboard, the replacement of capacitors is more a question of security, than a question of quality.