Take a look at what REL provides for their speaker level connection.As a Rel B3 owner I thought wire is wire since the Rel has such a high impedance. But after reading a lot where some folks said it made no difference and others said it made all the difference I decided to try a Nordost Baseline. It did make a huge difference over that aluminum cable that came with the B3. Better attack and decay. It cleaned up a muddy sound I didn't think was there.
That being said I'm stating my thoughts based on Rel ownership with the stock Rel cable not any other brand.