Which power cord should you buy first

My experience is that the most noticeable changes to a device when a alternate Power Cable is added, is on SS Devices. In my case this is a CDT.

When adding the same Power Cable to the DAC, change to the end sound is detectable but not to the measure of the CDT.

In my case the Power Cable selected also has produced a change to the end sound that is perceived as a betterment on both devices.  

It pays to experiment, but with my specific gear, power cable was better on the source first. 

I realize this is an old topic.  It's good getting current experience.   Appreciate everyone's input .  My Pass labs 350.8 amp comes with a pretty beefy power cord with its own direct power line.  I have a separate Lumin U2 streamer and La scala DAC.  Sounds like experimentation is in order between these.  Thanks again 

@salc trying is the only way to find out. Everything matters.
However based on my experience, I follow a simple rule as I proved over and over it works every time - start from speakers and go up the chain - speaker cables, amp power cord, interconnects into amp, etc.

Plug the amp directly into the wall outlet without power conditioner

First power cord upgrade is for the amp - 10awg minimum, best possible cord you can afford

Second is for the preamp. Then on power conditioner feeding source components, then up the chain - preamp, DAC, streamer/transport

Also, I owned 3 Pass Labs amps - X250.5, XA30.8 and X260.8 monos. The generic 14awg stock power cord included with the amp is enough to get you up and running. But…every time a good power cord made a difference on these amps in my system. Even the affordable Audience Forte F3 beats the stock cord.