[markC]

Anyone know off hand how low of an impedance a 627 will drive without getting into trouble?

[peranders]

It can deliver at least 40 mA (with proper cooling) but if you were thinking of a pair of headphones with 100 ohms in series I'd say it would be possible although a buffer with be preferred like BUF634 or the new LME49600

[markC]

I'm actually loading the output with a pair of resistors used as a voltage divder for my Dac. The load is 105 ohms and proved to be too low as the dynamics are squashed. The punch and liveliness of the music are restricted. I've come up with a new scheme which will present a 647 ohm load. I'm hoping this will be the ticket.

[peranders]

105 ohms is a tough load for the OPA627 if you want the highest possible performance. A buffer is recommended. Depending of hof your signal source look like you have also the TPA6210 which can deliver 500 mA! at extremely low distortion levels but notice that this is a current feedback opamp.