Linear Power supplies for DACs...?

SMPS  can be better depends on who makes it and what it's  in.

THIS MYTH GOES SOMETHING LIKE THIS:

"Switching supplies are noisy."

"Linear power supplies are best for audio."

We disagree!

About 5 years ago, Benchmark stopped putting linear power supplies into our new products, and we replaced them with switching power supplies. We did this because linear supplies are too noisy. Yes, you read that correctly, linear supplies are noisy! A well-designed switching power supply can be much quieter than a linear supply.

LINEAR POWER SUPPLIES CAUSE HUM

The noise problem is due to the fact that linear power supplies have large transformers and other magnetic components that operate at the AC line frequency (50 Hz to 60 Hz). These line frequencies are audible, and we are all too familiar with the hum and buzz that audio products can produce. It is no secret that this noise is caused by the power supply, but few people understand why it can be so hard to eliminate. Most people think that hum is caused by conducted interference (AC ripple on the power supply rails), but this is rarely the case. Most AC hum is caused by magnetic interference, and this can be very hard to eliminate.

Anyway I wasn't referring to only LPS or power supply  in general  but any noise in the signal that can get to the speakers. Power supply or transformer hum is harder to get rid of short of replacing the offending item or getting rid of the component. 

If not, buy a new DAC yours must be pretty old and junk since even cheap ones now have pretty good filters. In others words it's  placebo. Good modern DACs  work really well with whatever power supply they came with.

I've lived in 8 residences in the last 20 years and never had or heard any hum. I've never noticed it with wall warts or linear in amps. This thread is about DACs and if a linear would improve or is it placebo so whether you use linear, switched that came with the DAC it doesn't  really matter since we don't  listen to those wires anyway their waveforms are filtered by the DAC. 

If you turn your system up with nothing playing and hear hum then you need to look for the culprit unless you're using tube amps sometimes they will have a small hum. Other than that a good DAC should filter any power supply noise out, nowadays even a cheap DAC should. 

I'll be sure to stay away from my wall warts with a portable transistor AM radio. I have a wall wart for a DVD player plugged in my panamax conditioner with my other stereo components never had a problem. Just use what comes with your DAC if you can actually hear it make noise then by all means replace it but replacing it with a linear with never hearing any noise doesn't make sense.