discrete transistor designs only have technological advantages in a few situations relevant to head-fi - can handle higher V, and current than many op amps, special audio power "chip amps" do cover higher V, I ranges to a degree - but we still have to go with discrete for ES headphone kV needs
for many dynamic headphones properly selected, applied monolithic op amps can handle enough V, I - there are hundreds of models, some part #, designs dating back 30 yrs - not all were ever "good for audio"
the last (little more than) decade has seen a huge investment, competition to meet the demand for improved monolithic op amps for medical imaging, Telcom A/DSL - there has been a step change in the performance available in today's best monolithic op amps
much of the "discrete is inherently superior" claims date from long ago, have been obsoleted by especially the last decade's new op amp's advances in internal designs, semiconductor processing
a monolithic op amp design can still use extreme quality passive components for inputs, filtering, feedback, power supplies
Linn long ago made $3k + stereo audio power amps with power "chip amp" internals
my diy composite op amp headphone amp (my avatar) uses more, and more expensive chips than that Linn amp
Edited by jcx - 1/5/12 at 8:55pm