The OPA627 is one of the most faked opamps around. It's a really great opamp, just make sure you get it from a "Texas Instruments" approved distributors. Or you will end up with a fake and say it's so so and nothing to write home about.
These type statements regarding the sound I would bet are from owners that have gone looking for the best priced ones and got fakes instead.
http://www.ti.com/info-store/distributors.html?keyMatch=authorized%20distributor&tisearch=Search...
Cheers George