For HD650, I still like the Equinox best, it doesn't change the character of HD650 but embellish it, making everything better/bloom, preserving the beautiful smoothness of HD650. It's like changing from a Target black suit to a Georgia Armani black suit. Still a black suit, but much better. The Equinox is my favorite and basis for comparison.
The silver Dragon (SD) was a bit dry, and the treble was brighter, but very detailed.
I feel the RAL and SD cable changes the HD650 to the extent that HD650 is no longer HD650, for good or bad. For the same money/effect, I might just get DT-880, 990, K701, or a Grado. I strongly recommend against buying an RAL, though, as I am considering filing a small claims suit against RAL after unsuccessful attempt to obtain refund or the cable that I paid for 3 months ago, after BV promised a specific time to deliver but failed to AND stopped responding to emails, and phone lines no longer work.
The Cardas is well extended clearly better than stock cable (improvement worth the price). It's more exciting/lively than Equinox but not as smooth overall. Doesn't change the HD650 as much as the RAL or SD, but not as smooth as Equinox. Overall build quality is also the last place of all cable mentioned in this post (IMO), though this does not necessarily affect durability.