is it possible to bias opa627 into class A?

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Class A depends on load - for driving a 50 kOhm volume pot most op amp outputs factory internal bias already is Class A

so you really have to know the signal, load - and the limits of the op amp - many may additionally distort from current drain that is even a modest fraction of their rated output

careful meausurement of actual op amp with load is needed to see if, or by how much you are improving distortion - often a 2x THD reduction is all that is found

2 op amps can be paralleled, biased "against each other" in push-pull, of course with significant Class A current bias you have to deal with the heat:

http://www.diyaudio.com/forums/solid-state/114858-opamp-based-amps-question.html#post1392458

I like multiloop composite circuits - use the OPA627 as the input and global feedback stage around a 2nd op amp with much higher current specs - easiest to compensate with a really fast output op amp - like a CFA - TPA6120/THS6012 is great for line driving, most dynamic headphones:

http://www.diyaudio.com/forums/solid-state/45794-high-loop-gain-composite-op-amp-circuits.html
 
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