Linear Power supplies for DACs...?

Is there real SQ benefits or is it placebo snake oil?
i have a Chord Qutest and it has a wall wart. Lots of people say there’s real benefit to adding an external LPS. 
Plenty of choices ranging from $50 - $500.
Sure, a home audition is ideal.

but, what do you guys think?

Not just for the Qutest, but in general for DACs.
I'm using a TeraDak DC-30W LPS from Taiwan ($100++) for my Chord and it does the job; I hear the difference. 
I have a Qutest as well. Started with the wall wart, switched to a battery, then got a Teddy Pardo LPS. The Teddy Pardo is amazing, and I've bettered it by using a deep cycle battery and pure sine wave inverter to get completly off the grid(for the backend of my system).
Ian, in your case the LPS Farad3 psu is one of the best in the market. An excellent choice is also theSMPS from SotM Sps 500 with a clean filtered PSU.
Just a report back:

I bought a Teddy Pardo LPS for ,my Chord Qutest and it has made a very substantial positive impact.

More depth.
More layers of sound.
Fuller sound spectrum.
Deeper tones.
Greater separation.

Very dimensional and a true sonic upgrade. I am very pleased.
I recently made some improvements to my front end which includes a linear power supply for my CD player and battery power for my tube preamp buffer. Things have never sounded so analog. Digital glare? What’s that? I also added a VPI brick on top of the LPS transformer. Seems to help smooth things out. Strange.