van den Hul 3T new cables Mountain and Cumulus

In '80s I was introduced to VdH speaker cable via Excel Hi-fi Co. in HK. It was a great improvement over the Monster I was using. That was upgraded to Magnum in 2010. My confidence in VdH cables grew as I discovered Rain Forest, a small but high quality record company in Guangzhou deployed VdH cables in all areas of production. I bought Jubilee XLR for CD to amp shortly thereafter. This year I upgraded my system with a new CD player and pre/power amps. Jubilee is used with the amps while I use the Hill (3T) for CD. My brother bought the River RCA as a gift for a friend yesterday.
VdH cables are very transparent and extended in FR. Dynamics is not a problem.
They are also neutral and so coloration does not occur to an audible or significant extent. Bass digs deep and is well defined. This exemplifies with classical music with much bass energy. With rock and pop you do get a touch of excitement but I have to say punch and throbbing of chest is limited. In summary they are all able to aid reproduction faithfully. However, if you are looking for drama in bass, you may need to look elsewhere.

Like you, I am a fan of vdH, and have found the First Ultimate to be my reference, and in fact could not pick a huge difference when compared to, even, Indras. I have since got 2 pairs of the Mountain, phono-pre and pre - power. Just can't fault them, they seem to not add or take away anything. No harsh edginess, but fine detail micro and macro dynamics, and superb bass just everything well balanced. I must say I have used them in a Electrostatic/Valve amp, and cone driver solid/ state systems, and have always preferred them to all other cables that I have tried. Having bought more expensive cables, that I wanted to like, after a few weeks I always went back to the vdH cables. I suspect there are heaps of audiophiles quietly using these in their systems, but because they don't bring out a new model every year or charge 5 figure sums they don't register on the high end reviewer's radar? The Cumulus interests me, but that is a little pricey to buy without an audition, currently bi-wiring with the revelation, and happy.
In summary, as far as I know only Stealth and vdH are making amorphous metal, and carbon cables, everyone else is using 99999999 copper or silver, I am impressed by The Mountain, and you will have to pay 10 x the price to get marginal/questionable improvements. Just my tuppence, for what it's worth.

I'm using The Cliff 1m & The Mountain 1.2m
I've used to have The Cloud, but unfortunatelly it seems that swallows my passive controller/SET 300B and my Lowthers could not follow. This cable is better on all aspects over The Inspiration, but only if your amplifier has A LOT MORE POWER RESERVE than your speaker's needs. The Air has the same character but less bass and less demands from your amp also. The Inspiration was (and still is) the all-round reference without any special demands, but while it offers excellence on every parameter, it really falls behind the 3T Air and even more farther than The Cloud (which it takes less than a minute to confirm it's superiority).
The Orchid is better than The First in the same way that The Inspiration is better than The Revelation (a whole world of difference, with upgrades and improvements that makes me to abandon my lifetime preference for Cardas). From there, the elevated quality to The Mountain, is unimaginable!
For me, The Mountain is the instant classic and the best IC for music listening.
But after having (one of the first ever produced 4.5m of) The Cloud for a year, I'm in a very difficult position to recommend it for anyone other than the kilowatt lover who also uses an active preamp! As for my quest regarding the SET 300B/Lowther PM7A matching speaker cable, I really don't know what to do, as I reluctantly refuse to buy for a second time The Inspiration. Make no mistake : The Inspiration is a world class reference speaker cable, although if you ever have the chance to listen to a pair of The Cloud in a solid state amp of over 150w with an active preamp, you will not going back to your usual reference! The improvement is beyond description. Even me, with my 12w 300B SET and my Lowther PM7A which were asking for speed, clarity & transparency, I can see the new founded beauty of the Cloud.
Mr VDH is very productive in making his talented ideas come true. As with his Colibri, the offering of this 3T series of cables can cause an eyebraw extented far more than the audiophiles' expectations. He makes me a fun & a believer.

PS 1: The Cumulus was not available then and The Air was offered as a special order only for studio applications.

PS 2: What the OP asks for, has allready acomplished with The Orchid/The Inspiration a few years ago. What The Mountain/The Cloud is all about, has to be heard to be believed!
A new approach that confirms the growning good taste of the master VDH. A statement of what we have lost in those years in hunting for the sterile hi-fi artifacts.

PS 3: The Orchid's performance is very near and clearly comparable with The Platinum! (The fact that betters the MC SILVER IT MkIII by a milestone! ... has kepted as a secret among the reviewers and the few souls who spend big $$$ for having it, but I feel that it comes the time for VDH to erase a lot of his previous models ASAP).

I tested a 4m version of The Cloud against a 1.5m version of The Super Nova recently.

The Cloud was hands-down faster and more transparent than the Super Nova, to a degree which surprised me. I own that Super Nova cable, and have had to put it up for sale and go forward. Only issue for me is to see whether to purchase a set of The Cloud or even go to the full extent and listen to The Cumulus.

I must admit I was a bit stunned, as I didn't expect much difference between the two cables.