Sean - I’m a bit confused - unclear how long a run you’re talking here, 9m or 3m? But that seems to me somewhat more about cost, as good cables will work pretty well over fair distances, otherwise nothing much would ever get recorded ; ). Fretting over impedances, etc. in advance of listening is putting the cart before the horse. If you buy based on specs and don’t compare with something that may not meet that spec on paper, you’ll never know which sounded better, and you may have talked yourself out of something in advance that could be better.
Active monitors like yours are nearly always run in studio situations directly from a line out of a DAC with a volume control. I use ATC SCM25A’s in my home studio. Many like Mogami cables (on the affordable end of things - used by many studios), and sky’s the limit in the upward direction. Paul likes Boulder locals MG , but they ain’t cheap (and I believe he has said he doesn’t like Mogami - but that’s Paul in Paul’s system, which is not you and yours). There’s a thread on here on Belden Iconoclast which many there seem to like as well. My guess is that for the price of 9m of some of the pricier cables out there, you would be happier with the sound of a BHK with two sets of shorter, cheaper cables. But not knowing your budget…
The volume control in the DS DACs is one of the better volume controls you’re going to get, despite the fact that you can go down the rabbit hole of worrying about what volume level you’re running at.
Given a good quality preamp, most systems actually sound better with one. A big part of this is gain staging, which is a main reason mrderrick’s attenuator could concievably sound better than nothing. Having said that, I’m currently running my DSJ directly to my Harbeths’ amp and subs (since Redcloud, anyways).
As you note in Ted’s reply, professionals typically don’t worry about this sort of stuff. And the Cable Co. is a great option.