Shielding can be a mixed bag depending on application. Some of the things to be wary of are the shields acting like antennas, and adding capacitance to the cable. There's also a difference between electrical and magnetic shielding.
For power cables, shielding is not really necessary from the concept of keeping the power "clean". The magnitude of the waveform from the wall is ridiculously huge compared to what could possibly ever be induced by a "noisy" environment. The power supply in your device is already going to rectify and regulate everything coming in; if it can't handle a bit of scratch that's literally a million times lower in magnitude, then you've spent your money poorly and should probably buy something with a more robust psu. You've also got a hundred feet of copper wiring running through your walls going from the panel to your outlet and passing near a fridge or air conditioner at the same time. Adding a shield for the last couple feet isn't really going to make a difference. Capacitance in a power cable is also highly undesirable as this will restrict actual power flow, though this concept is less important for something like a dac that doesn't draw much power. One potential application of shielding on a power cable though would be to try and minimize "noise" from getting out, but shielding doesn't quite work as well for containing as it does for, well, shielding.
Shielding on interconnects is another matter however, since the signal levels here are much lower and closer in magnitude to what could potentially be induced by noise. Interconnect signals are also typically amplified, meaning any noise picked up will get worse coming out the other end of your device. In this case, shielding is useful as long as you didn't turn it into an antenna. The downside again though is capacitance, which will interact with the load impedance and create a low-pass filter, meaning you could potentially reduce your frequency response at the upper frequencies (there's additional issues with digital transmission as well).
Really the best practice is just to ensure ample space between cables. Long tight parallel runs should be avoided if possible; crossing at 90 degrees or haphazardly at odd random angles is better. Try to keep high level signals like power and speaker cables away from low level signal interconnects. If you have concerns about your environment harming your interconnects, then shielded balanced cables are the way to go.