Question About NORDOST cables

I got a pair of Red Dawn II speaker cables. I was really impressed by these cable; the speed, dynamics, vocals - it's transformed the sound of my system. unfortunately not all is good; the bass suffered from a major roll off, and to make matter worse it's also lost its definition. really bad.

if it wasn't for the bass I'd hit the jack pot with these cables. I really like what's done to the system. in fact, I just got a pair of Heimdall's IC's. there's a general improvement, and the bass has also improved a little, but I feel like there's some kind of imbalance between vocals and other instruments.

the Red Dawn has to go. that's clear.

what I'm not sure of is whether I should stay with Nordost, and upgrade to the Heimdall's speaker cables, or move to something else. I'd really like to get the Siltech 330L, but is out of my budget atm. I can get the Heimdall now, or wait until have enough funds for the 330L's.

I really could with some other opinions/thoughts on the matter.
many thanks,

Massimo

speakers: Paradigm S1v3(P-Be)