Now, as for DAC I-V conversion...
Generally, a current cannot be used to drive another piece of audio equipment. So when a dac spits out current, we need to convert this to a voltage signal. In any case, most DACs aren't designed to directly drive any kind of a load. DACs usually have sensitive internal circuitry which could be upset by any kind of non-specified impedence connected to the output.
Burr-Brown R2R multibit dacs for instance have the current output you describe, and in order for the chip's current sources to operate correctly and consistently, the output should be held at ground potential. This is one reason I shy away from using a resistor for I-V conversion, since output voltage introduces non-linearity into the DAC. That is, the size of an LSB step changes as the output amplitude increases.
Most often, the current output is sent into a virtual ground node at the inverting input of an opamp. A resistor from opamp output to negative input generates the output voltage from the current, since the current flowing into the opamp input should ideally be zero.
Obviously, a high-grade opamp is required to extract the best performance for this rather delicate task... often favoured are the OPA627 and AD811. These are both low-noise, fast opamps, though the OPA627 should give a lower overall noise, depending on the value of the feedback resistor used (not that it matters much... either will give excellent performance). The AD811 is also a different type of opamp, though in practice, it is used the same anyway. A low-pass filter is a Good Thing(tm) to use after this stage, to remove high frequency components from the signal and prevent that trash from getting into your preamp and poweramp circuitry. Finally, an output buffer of some sort is necessary to drive the interconnect and preamp nicely.