I suspect the fire alarm cable sounds good but, why stop there? The mc cable shown below has three 10awg connectors (H/N/G) and a metal casing that can be connected at the source end for shielding.
Unfortunately, solid core wire has poor flexibility and can only safely be used in fixed installations and not in situations where the cable is subjected to being flexed due to the risk of the conductor and/or insulation failing if moved repeatedly. This is probably why more audiophiles don't use Romex as power cables.