How would you compare Acoustic Zen to Nordost

WELL SAID! I agree completely.

I wouldn't use the Quattro Fil because it's not well-suited for fast digital sources. It's better for line level and phono signals. (That's why it's the one cable Nordost makes with a 5-pin din connection on one end to connect it to tonearm wiring.)
Why not use it? While most cables Nordost makes are fast like the SPM and propagate a signal at 99% the speed of light, the Quattro Fil lags behind at only 95%. Unsurprisingly, given its slower speed, its capacitance is 50% more than the SPM: 12.0pF/ft vs 8.2pF/ft. You don't want a cable designed that way for your intended use.
Acoustic Zen's Silver Reference mkII, on the other hand, is a good match for a digital source. It's fast, very musical, and highly detailed, especially in the upper mids through the high treble. For your application, given you have a mild hearing loss in the top octaves, it's perfect. You will never hear "too much" detail in the top and confuse that with coloration, IMHO.

Quattro Fil is old tech compared with Nordost's new Valkyrie (sp?) cable in the same price range.

Unlike many posters, I've actually had both cables - at the same time. My Arcam 92 has dual outputs...so, I plugged one run of RCA 1m Quattro Fil into one output, and one run of RCA 1m Acoustic Zen Silver Reference Two into the other output. Both cables were well broken in, and terminated by manufacturer. Tested on a Sonic Frontiers Line 3 driving an EAD PowerMaster 2000 powering Revel Studios. Every thing is very well broken in. A-B'ing was simple, just change the input on the preamp using the remote.

In addition to this, at the same time, I purchased two pairs of each of the cable's XLR 1m versions (for biamping). Of course, it was harder to A-B with these, compared to simply changing inputs using the remote...

So, what did I hear? First, the cables are VERY similiar. They are both easy to like Essentially, the Quattro Fil had far better bass extension and decay in the low-end, less colorolation in the mid-bass, and far, far better decay on the high end. Its true that the Acoustic zen has more coloration - but please please please recognize that it is an EXCELENT wire and this is a minor difference. I definitely would NOT say they were warm, colored, etc...they just weren't as neutral as the Quattro Fil. I tested this using a couple of well-recorded classical CDs, as well as on some modern pop.

I sold all the Acoustic Zen and kept a much more expensive Quattro Fil setup...until I purchased Discovery Cables for my new single-ended tube setup. WOW...you have to try these...forced me to put my Quattro Fils up for sale.

With all this said, I sold my Red Dawn II speakercables and put in Acoustic Zen Hologram II double barrels. A bit difficult to deal with due to the thickness. However, they are outstanding values. I would have loved to put in Nordost SPM or Valhalla, but they were so expensive for bi amping, so I chose the Zen...great bang for the buck, 90% of the performance for much less. Also, after living with the ribbon cables Nordot makes, I will say they are VERY difficult to live with. They are very easy to kink and to expose the wires. Quattro Fil is far easier to deal with...I'll never own another pair of high end ribbon cables that dont have durable shielding.

Of course, I'm also selling Zen these double barrels, too, too, because of my new monoblocks that dont require I use 10' runs...Discovery cables, my new speaker cables, are soooo great...I didn't even consider anything else :)

Good luck and great listening!

Interesting. I started with balanced Red Dawn and Pro-Silway MkII off my EMC-1 UP, findng both a bit lean. Discovery Essence was better balanced, but didn't provide the lucidity of the top octave I was used too. A great deal on used SPM XLR did the trick: all Nordost's transparency but with a fuller balance. Liked it so much I then took advantage of 1/3 SPM list used pair pricing to upgrade the speaker cables as well. I haven't tried the Quattro, and probably never will, understanding that its genesis was prompted by a NY dealer who simply strongly suggested that Nordost come out with a shielded interconnect for the noisy Big Apple grid. (Hence the greater capacitance, and probably inductance too.)