I think it depends where you plan on using the cable.
The reason I say this is because recently I changed my source to pre cables (AZ WOW) with my pre to amp cables (AZ Matrix Ref II) and was bowled over by the difference. With the WOW between the source and pre amp there was more extension and clarity, with the Matrix Ref between source and pre it was noticable smoother but quite a bit less impact and more ill defined. I expected a difference but not this much.
This is why I think the headphone test would be valid only if you tested cables in the spot you intend them to go in your normal setup.
The reason I say this is because recently I changed my source to pre cables (AZ WOW) with my pre to amp cables (AZ Matrix Ref II) and was bowled over by the difference. With the WOW between the source and pre amp there was more extension and clarity, with the Matrix Ref between source and pre it was noticable smoother but quite a bit less impact and more ill defined. I expected a difference but not this much.
This is why I think the headphone test would be valid only if you tested cables in the spot you intend them to go in your normal setup.