Prevent loss of Large Signal Voltage Gain at low Rload
You need an opamp with more output current.  Search for power opamps. (LM675 and OPA544 are two I've used.) At 200mA you might get away with a TCA0372.   Or use some audio driver chips if you don't care about DC.   

Edit:(more thoughts, comments)  Warning the LM675 has a minimum gain of 10.  And all the power opamps I've looked at have some cross-over distortion. (Still looking for the perfect power opamp.)  If your output is single sided, then you could use a transistor (Class A) with the transistor in the opamp feedback loop.. but that will waste a lot of power.  Or make you own push-pull output stage.  (again as part of the opamp feed back loop)