Hey all. I noticed a lack of reviews for Null Audio products on the web, so I decided to do a short one now that I received my Ethos IV. Now, until recently, I wasn't a cable believer at all, so please bear with me on this review. I've done several reviews of other products, but I don't have a format for cables yet. 
I purchased the Ethos Mk. IV with my own money direct from Null Audio via their website. I am not affiliated with them in any capacity.
Unboxing and accessories:
The Ethos arrives in a white cardboard box with a magnetic clasp. Inside is a fairly large zippered case, within which are the cable, cable wrap, and a plastic ownership card. The case is quite large, and seems rather sturdy. I would find it cumbersome if only carrying one set of IEMs but, as it so happens, it works wonderfully to carry my E1DA 9038S and its respective cables, in addition to the FDX1 attached to the Ethos. Effectively, this holds my entire IEM setup, so I enjoy it quite much. The ownership card is a nice touch and, all in all, I am pleased with the unboxing experience.
Build:
The Ethos is constructed of silver-plated UPOCC copper in a Litz 5 configuration. It is a twist, rather than a braid. The positive and negative conductors are separated within the same sheath and twisted around each other in a helix. Due to this setup, the cable is on the thin side, but it doesn't seem fragile at all. The rose/chrome Luka hardware is of high quality, yet quite lightweight. It doesn't have that flashy, "premium" look like a lot of pricier cables, but it is subtly attractive.
One small gripe is the use of the older-style non-split MMCX connectors. When I first connected them, they were quite loose on my FDX1, but I was able to tighten them with the adjustment ring.
My only other complaint regarding build is the ear hooks. While they are actually quite pliable and seem fine, I had requested that my cable be shipped without them. In a sense, this is really a QC/CS issue and not a build issue but, for a product that is custom built per order, I think it's relevant to list in this section.
Sound:
I tested the Ethos from my Samsung Galaxy A20, using UAPP, and an E1DA 9038S. My JVC FDX1 are the only IEMs used in this review, so my comparisons will be made to the **** 6 core SPC cable I had on it before.
Compared to the ****, the Ethos seems to tighten up the bass and improve treble clarity while leaving the mids more or less the same. Everything in GoGo Penguins self-titled LP just seems more crisp and well-defined. The uppermost treble has become more apparent (something I find lacking in the filtered FDX1) and separation is improved. Similarly, the lowest bass notes seem to be tightened up, while reaching the same degree of extension. All of these changes are rather subtle, but indeed noticeable.
At $70, I think this is a sweet spot for cables. The workmanship of the Ethos IV is top notch, and it sounds fantastic. I just wish their customer support were a little more attentive.
I purchased the Ethos Mk. IV with my own money direct from Null Audio via their website. I am not affiliated with them in any capacity.
Unboxing and accessories:
The Ethos arrives in a white cardboard box with a magnetic clasp. Inside is a fairly large zippered case, within which are the cable, cable wrap, and a plastic ownership card. The case is quite large, and seems rather sturdy. I would find it cumbersome if only carrying one set of IEMs but, as it so happens, it works wonderfully to carry my E1DA 9038S and its respective cables, in addition to the FDX1 attached to the Ethos. Effectively, this holds my entire IEM setup, so I enjoy it quite much. The ownership card is a nice touch and, all in all, I am pleased with the unboxing experience.
Build:
The Ethos is constructed of silver-plated UPOCC copper in a Litz 5 configuration. It is a twist, rather than a braid. The positive and negative conductors are separated within the same sheath and twisted around each other in a helix. Due to this setup, the cable is on the thin side, but it doesn't seem fragile at all. The rose/chrome Luka hardware is of high quality, yet quite lightweight. It doesn't have that flashy, "premium" look like a lot of pricier cables, but it is subtly attractive.
One small gripe is the use of the older-style non-split MMCX connectors. When I first connected them, they were quite loose on my FDX1, but I was able to tighten them with the adjustment ring.
My only other complaint regarding build is the ear hooks. While they are actually quite pliable and seem fine, I had requested that my cable be shipped without them. In a sense, this is really a QC/CS issue and not a build issue but, for a product that is custom built per order, I think it's relevant to list in this section.
Sound:
I tested the Ethos from my Samsung Galaxy A20, using UAPP, and an E1DA 9038S. My JVC FDX1 are the only IEMs used in this review, so my comparisons will be made to the **** 6 core SPC cable I had on it before.
Compared to the ****, the Ethos seems to tighten up the bass and improve treble clarity while leaving the mids more or less the same. Everything in GoGo Penguins self-titled LP just seems more crisp and well-defined. The uppermost treble has become more apparent (something I find lacking in the filtered FDX1) and separation is improved. Similarly, the lowest bass notes seem to be tightened up, while reaching the same degree of extension. All of these changes are rather subtle, but indeed noticeable.
At $70, I think this is a sweet spot for cables. The workmanship of the Ethos IV is top notch, and it sounds fantastic. I just wish their customer support were a little more attentive.
I launched a PayPal case two days ago and they haven't even responded to that!
If you want to go ahead and get scammed by (yet another dodgy) cable manufacturer, Null audio is the place to go!