For years now we've had folks online extolling the virtues of 'upgrading' caps and op amps in their devices, and some manufacturers like (Burson, Creative, etc.) even cater to the 'upgrade' crowd with DIP socketed op amps (which are pretty prominent in the SoundBlasterX AE-9 that was just announced for instance). Some people even go all out and just replace everything because of course more expensive parts mean better: http://hazarribas.blogspot.com/2012/01/modifying-musical-fidelity-v-can.html And some people sell modded equipment too (I posted recently about someone selling a modified Creek OBH-11 on ebay with quite the claims about their improvements). Yes there can be value to replacing capacitors in the sense that they are rated for a certain operational temperature and eventually most capacitors wear out and need to be replaced, however unless a cap is faulty (such as the blight that happened a few years back when some Chinese capacitor makers used incomplete design formulas stolen from Japanese capacitor companies that resulted in premature failure), a well designed product should mean cap replacement is a late in operational life task to perform, not something up front... otherwise why wouldn't the manufacturer at least offer a 'higher grade' of the product with the better caps to start with (and charge a decent markup)? It doesn't stand to reason that so many manufacturers would intentionally cripple their products out of the gate with substandard parts intentionally (not saying there aren't some design ignorant manufacturers, but I think it's a true minority overall). Regarding opamps, NwAvGuy wrote about them back in the day, and what he wrote makes sense to me: http://nwavguy.blogspot.com/2011/08/op-amp-measurements.html ...A lot of people play around with 'op amp rolling' but they mostly lack the ability to measure the results. A lot of op amps get 'upgraded' to much more expensive parts usually with zero real world benefit. Worse, these usually faster parts can easily be unstable in a circuit designed for a much slower part. Some of the differences heard could be high frequency instability. But when someone 'upgrades' to an expensive op amp with high expectations many assume the different sound must be better sound... What I'm wondering is, besides educating myself more in electrical engineering, are there any concise guides on whether any component 'upgrades' are worthwhile or not, and/or how to evaluate puported 'upgrades'? Or should I just assume 99% are bullshit and not waste my time even reading about them? I assume some of this stuff also falls into the 'hard to know' category because it involves in-depth knowledge about the design and layout of a complete board and it's components (and modern multilayer boards are not trivial to reverse engineer) and/or good blind testing of the upgrades (with at least some understanding of the impact on the overall design when changing out parts, i.e. not introducing unwanted long-term net negative effects on other components while achieving a short-term performance gain, or creating a performance gain that's only possible in a more narrow operational envelope without understanding those limitations). But I was wondering if anyone had any thoughts/advice on the topic, and if there are good books to go to on the subject, which ones I should start with.