They dont un-necesarrily burn out. Any good quality built amp should last for years and years as long as its hooked up and tuned properly. I'm sure amy amp in the category you are looking after will have longevity. The difference between BB and using generic branded ICs is the quality of build in how it relates to the quality of sound. Only some of the elitist of audiophiles ask for them by name. If you get BB parts you should be able to tell when the music is completely silent (no hissing on a blank track unless induced by head-unit or processor), and warmth/depth/fidelity/control at the highest of volumes.
For my repairs, I can pay $0.75 per opAmp for the TI or chinese equivalent, or spring for the BurrBrown parts which can run up to $20 a piece. Most amps have several to dozens of these parts.
Here is a good read on opAmps. BTW, the opAmp is the the first device in-line with any amplifier's pre-amp circuitry. If its a piece of junk (I've seen many in Amps which were never intended for Audio) then its probably not going to make the rest of the amp sound good.
http://tangentsoft.net/audio/opamps.html