OPA627 is generally regarded as the best audio opamp, period. Unfortunately, TI/Burr-Brown knows this and it's fairly expensive for an opamp (to be honest, it's based on circuitry that costs more to manufacture). The OPA637 is essentially the same opamp, but a bit more detailed. However, it is not stable with gains less than 5.
Either opamp is generally considered to be extremely rich and detailed, yet neutral. Some may regard it as a bit slow, but it never really sounds that way. It's not for portables, though, unless a lot of voltage is present. Generally speaking, it needs a power supply of 9V or more.
If you're starting from an NE5532, chances are you'll hear tremendous improvement with just an OPA2134 -very inexpensive and stable in more circuits than not.