Differences between cable sound.

I think that your friend should try a few interconnects without any prior knowledge of their material used in their construction. The objective here for him is to find the best sounding interconnect that he can afford.

Knowing from which material the interconnect is constructed (copper, silver or gold) is purely for academic discussions and the ultimate purchase decision criteria should be strictly how the interconnect integrates well in your friend's system.

I've seen so many systems poorly matched from audiophiles putting a lot of money on their gear and putting not enough money on their cables. They have highly resolving electronics which sound is downgraded by the poor system matching interconnect/speaker cables.

Use your ears and go for the best sounding interconnects.

Many cable makers have excellent return policies or you can use the Cable Company's lending library. They also give excellent advice.

Brownsfan,
I have used nunerous products from VH AUDIO and the quality is very high. Sonically they are stellar. I have used many of his caps and now wire. Definitely worth checking out.