I have one of the older style, braided Audioquest Hurricane Constant Current (source) cables that is 2m, and the rest are the new non-braided 3m Hurricanes.
I don’t know if it’s the length, or the fact that the Audioquest’s design changed (no longer braided). But, the new 3m power cords do sound clearer with more dimensionality. The old 2m cable was flatter sounding, but also more immediate. When I did the test, I was actually expecting the opposite. It pains me slightly not knowing if the differences I’m hearing are due to length or the fact that Audioquest adjusted their design.
I only started considering cable length when I, totally by accident when I wasn’t considering cable lengths, discovered that a 2m Nordost Valhalla 2 USB cable sounded far superior to the equivalent 1m USB cord. Another case where I would have been expecting the opposite if I was actually testing for it. That’s how big the difference was: I wasn’t even testing for the lengths or comparing between cables. I have a USB reclocker so need two USB cables and I was trying my system without the reclocker. I noted my system sounded worse than normal even without the reclocker, so I tried replacing the 1m cable with the 2m, and was quite stunned by the difference. I also tested the Audioquest Diamond .75m cable which sounded closed in compared to the 1.5m version.
A few audiophile contacts I have that are technically inclined and have nothing to gain by propagating myths tell me that for USB, 1.5-2m is best because of “reflections”. Something about the signal handshaking and having to “reflect” back I think. I don’t know if this applies to all digital cables or just USB. For what it’s worth, Nordost recommends 1.5m for “digital cables”.
After my experience, I begrudgingly accept the manufacturer recommendations on 2m for power cords (even though I’ve not proven length to be the reason for the difference I heard) and that digital cables should be 2m, and that analog interconnects should be shorter.