I guess it is more on updated cosmetic and marketing rather than fundamental changes on inside wires. Whatever it is, the difference in quality is very subtle and in term of price that difference is huge! Original retail price on AQ Gibraltar and castle rock is the same, knowing AQ Gibraltar is made like a few years ago where all those material, labor and everything else, were much cheaper! It is not an objective reasoning but it worth to think about it.
Besides, you have a 60 days return policy (at least what they say) with MicsicDirect which allows you to audition both AQs in you system.
on AQ Volcano, I am sorry, right now I am using those cables, I wouldn't be interested to sell them. In the mean time that you are making your opinion on Gilbraltar or Catle Rock, hopefully you might find a nice pair of AQ Volcano...
cheers.
