No the PowerLines are designed to decouple the audio units from mains socket so ideally a Power line is used to the hifi.
It’s wire is nothing special. It’s the decoupling plugs that do the magic. So If they aren’t connected to the hifi directly you get no benefit. If you have a spare one you can of course use it from the wall to mains block but I wouldn’t buy one for that purpose. A different cable where the cable is better but plugs are simpler might be better from wall to mains block.
If you want to experiment and have the skill & tools, it would be fun to replace the (I assume a bit ordinary) male to female IEC cables with something with better spec., and the same with the wall to Audiolab cable.
Something extra that it will help with is a cable bundle tidy up by making each cable to a customised length.
This can be done easily at a reasonable cost, or as with everything audio, mad money.