[Pangaea]

Is it possible to get a TOSlink cable that would hook up to the optical line out on an iMac that would then terminate with RCA(female) so you could plug in an amp. Would I need a DAC to do this?

 

[krmathis]

You would need en external DAC.
Since TOSLINK is a connector type for a digital (and optical) signal, while your amplifier most probably take analog single ended signal via rca.