@213runnin - I don't necessary agree that all interconnects in a system need to be solid core. Granted, that would be the best solution, but even just having one solid core is better than nothing. I would recommend this at the last point before the amplifier to "drive" the final sonic signature of cable charge/discharge characteristics.
Another comment. Some of these interconnects use a much larger 18awg solid-core conductor (such as Signal Cable or Beldon 1694 from Blue Jean). I have done a lot of R&D with solid core and have found that when conductors are larger than 20awg, then you start losing high frequency detail and clarity. The larger-core conductors would be very good for a subwoofer cable as the larger solid-core awg will convey much more power in bass notes. However, it's a fine line. I found 20awg to be the best all around. With 22awg and smaller, it will still work, but you start losing bass/midbass impact.