I actually did just compare these two brands, for speaker cables. I was using a pair of Acoustic Zen Hologram II and a friend strongly recommended trying the Audioquest Gibraltar which he was enjoying immensely. Since I found a good price on them from Music Direct (closeout sale), with a 30 day money back guarantee, I thought "why not"? So in went the Gibraltar's. Compared to the Hologram II's, the AQ cables were clearer and more extended in the high's. I wouldn't call them bright, but I'm sure that they could sound bright with some gear. The AQ cables also presented a more immediate soundstage, not as forward as some cables I've heard, but a bit too forward for my taste. In comparison, the AZ cables sounded more laid back soundstage, with a fuller and more musical tonality. Again, the AZ is not the warmest cable that I've ever heard, but I'm sure that it could sound too warm with some gear.
In the end, I sent the Gibraltar cables back to Music Direct for the refund. They were very good cables, much better than the old pair of AQ Midnight 3 speaker cables that I keep around as backups, but in my system, in my opinion, the Acoustic Zen cables sounded more natural, more musical, whereas the Audioquest cables sounded like very good hi-fi. As always, YMMV.
In the end, I sent the Gibraltar cables back to Music Direct for the refund. They were very good cables, much better than the old pair of AQ Midnight 3 speaker cables that I keep around as backups, but in my system, in my opinion, the Acoustic Zen cables sounded more natural, more musical, whereas the Audioquest cables sounded like very good hi-fi. As always, YMMV.