# OFDM DA conversion problem

I'm working on a sound card based OFDM system and ran into some problems:

How can I perform DAC on the real and imaginary parts of the IFFT? I think they are real numbers instead of 0 and 1. Thanks.

$$z = 1 - 2j$$ $$\mathsf{Re}(z) = 1$$ $$\mathsf{Im}(z) = -2$$