It depends on the power supply quality of the hub, the power demands of the DAC, and the voltage regulation capability of the DAC. These things are all variable. If the DAC is limited on its own capability of regulating voltage, then a powered hub may make things worse, because the powered hub's voltage supply may be from a cheap, switching supply. If the powered hub is from a high-quality power supply, then it will make things better. On the other hand, if the power demands of the DAC are high, but onboard voltage regulation is great, then a sufficiently powered hub may make a lot of positive difference - especially if a laptop is in the equation (never enough power). An in-between DAC (low-power, but poor voltage regulation) may be at the complete mercy of the power supply - either PC or powered hub. Even the cable may have effects when it comes to the power supply.
Edited by tomb - 8/28/13 at 4:52pm