This is one of the MOST important things you can read.
If you go to various Audio Forums you will always hear that you should 'upgrade' Op Amps, Capacitors, and so on...
But more often than not, you will get mis-information, often by people whose business is the modification of equipment!
They make money ONLY if they can get you to modify your equipment - so they tell you that you really need to do it of course !!
They use mystical and unverifiable subjective words like 'more air', 'better definition', or they misuse technical terms
like 'Headroom'... saying lowering noise by 2 db automatically gives you more 'headroom' (it doesn't).
They say you need a 'better high quality Op Amp installed.... or special capacitors...
Great Article on 'Op Amp Myths and Truths'