Cable for lowend More Full sounding

I have a biamp situation with tube upper and solid state lower, Crossover is 200hz Von schweikert
I am using Audioquest Midnight for the lows, Well controlled but dry,Can i improve on that?
Look at Purist a much better cable not cheap though but it depends on the model.
lower to mid cardas will roll the highs give you a sense of more midrange and bass presence
Good heavy COPPER wire, with red copper ends will work perfect.
#10 @ 3-5 meter
#12 @ 1-2 meters

Make sure whoever makes them twist the last 10-12" the direction of the stands in the construct, CW or CCW. It may sound weird but it really does help.

Some people like med to heavy copper bottom to top. That twist is for noise but it does "SOUND" different if you twist by the natural weave of the copper. All my materials are Clockwise, so I twist the last 12" CW at two twist per inch for # 12 - 8, more twist per inch for anything smaller.. That will cover a single wire run also (Non biwire).

BTW that construct will fatten the mids and can tame a harsh hard dome a bit, too. Works better than a network box in the cable .. :-)

T12-24 # 22 N5 copper (weave) or better is a serious cable to beat too.. Just a DEAD quiet heavy load space age tech cable. I got a pair cookin' right now.  106.00 usd gold over copper ends. spades. VERY much worth the wait.. 2-4 weeks. I did get one set in 5 days though..

1-200.00 3 meters or less for a pair.. 2 weeks from CHINA.. OH yes, CHINA.. I've just been blown away.. The 90% silver clad teflon ribbon cables.. Mercy do they sound good.. 120.00 usd 3 meters..PAIR..

No solder. LOL If you/they use some contact enhancer that is a GREAT idea. Locktite the set screws.
I read on another site that someone stripped their Midnight cable at the 18GA setting. That's too thin for bass duties. On my bi wire set up, I use 10GA (stranded silver) for the lows and 16GA (solid silver) for the mids and highs. The sound is fabulous compared to my old set up using jumpers. 

All the best,
Put mid-range Wireworld on the upper part.  It will let the bass come out.

Of course, room treatment will affect the sound much more than cables.
Larger conductors (heavy gauge) would do the trick, for instance Deulund 12 awg cotton in oil. Cables are inherent ton controls....