One thing you may want to try is to plug your stock power cable back in to see if the highs return. I have a couple of PS Audio Plus's and a couple of Statements that I just received, but have not installed yet as they are not quite "bendy" enough for my setup. I also have a Shunyata Snakebite which is that run of spare Diamondback cable they had with the cheaper connectors. (If I remember correctly) I have that on my phono preamp with great results. I may try it on my VK 31SE as well. I'll have to update later on this.
Cheers,
Paul
Cheers,
Paul