Introduction
So it's a cable.  It's copper.  It's coiled into a helix pattern apparently.  It's $36 +shipping and it most definitely works.
 
 
 
Construction 
Quality, flat, with nice chunky plugs that are easy to connect.  It's purple.  I like purple. 
 
Sound
I wasn't expecting this cable to make a difference but the minute I plugged it in, I heard more soundstage and a bit more clarity.  Things were separated and detailed.  The bass was across-the-board impactful and boosted.  This was the experience that converted me.  Along with the story hidden above in the spoiler. 
 
Equipment used - Tidal streaming HIFI CD quality (44khz 16bit) - Hifime Sabre 2018 USB DAC - Cayin C5 Amplifier - 
Headphones - Beyer DT770 250 ohm, AKG K712, AKG K7xx, Sennheiser HD600, Grado 325e Mahogany tuned
 
Notes for specific cans.
Beyer DT770 250 ohm - Bass impact, speed, soundstage, clarity
Akg 712 - Bass extension, soundstage
AKG K7xx- Ditto
Sennhesier HD600- Clarity and treble
Grado 325e drivers in Mahagony cups - Impact, speed, energy added to an already energetic pair of cans.  
 
Verdict
For me, it's a no brainer.  So well worth the price of admission for my portable setup that I take to the office. This cable will not break your bank, your significant other's heart (I think that starts at around $400 a meter) and you will hear and feel the difference.
 
Rish out
Happy listening!

This little DAC punches way way way above its weight.  
I fell deep into the audiophile hole about a month ago, waiting for our 2nd son to be born.  If I could be so bold, I went through a rebirth.
I bought a Chord Mojo (Which I will be selling by the by, explanation to follow) and I prefer the sound of this little DAC coupled to the Cayin C5.
 
The Mojo is exemplary and quite possibly future proof save for the advent of holographic audio, but this little sabre dac made by some DIYers is on par with it.
CAVEAT - when amped!  Get an amp, please.
 
I did some A/B testing between the Mojo and the Sabre DAC+Cayin C5 combo and found that I preferred the Cayin's smooth sound and possibility of bass boost.  I'm not a basshead but I do find myself fatigued by too much treble.
 
The Chord is on another level, but that level - for me does not justify the $300 price difference as of this writing (9/2016)
1) Chord Mojo - $599 
2) Sabre DAC $82 + Cayin C5 $129 + Camera Connection Kit $39 (usb3 version) + Wireworld 3.5mm cable $42 = $300
 
EDIT - Important distinction for hours of unfatigued listening - the bass boost helps.  It smoothes out frequencies.  If you want to listen for a short time and in reference mode, turn off the bass boost and enjoy you'll get 8/10ths of the way to the mojo (again you need the amp).
 
But I digress.  The Sabre DAC is the backbone.  If you don't have audio files north of 96khz/24bit then you are golden with this DAC.  I stream Tidal hifi and find my involvement with the music soaring. With this combo, I want to listen to everything and good recordings or bad, they both sound good through this DAC + Amp combo.
 
And if you want a portable audio solution for your office and commute, you can't do too badly by this combo.  Even the DAC itself will power a wide variety of headphones.  I plugged my Beyer DT770 250ohms into it directly and am quite happy with the sound!
 
Get it, you won't be disappointed

I love the Beyerdynamic dt770 250 Ohms.  After searching high and low for a closed back headphone I fell upon these knowing that I would carry an amp.
 
With the Cayin C5 - High gain at about 2.5 volume and yes, some bass boost - they sound tremendous.  I feel an impact of the bass, I feel a sound stage, I hear vocals and I'm enveloped in a lush sound.  Great for instrumentals.  Great for well recorded music, great for all genres.
 
However they do leak some sound.  Be prepared, you won't hear the outside world but if it's quiet around you, the outside world shall hear you.
 
That being said, go for these, get the Cayin C5 and be happy.
 
If you need to drive it from an unamped source they will sound a tad harsher BUT still great.

Folks!
 
Just found the joys of tube audio and have to say this little guy opened my ears.  I did a lot of research here and on a few other sites and bought 3 NOS tubes.  I realised that with my renewed interest in headphones and building a dual speaker and headphone capable system I needed a tube in there somewhere.  I don't have the cash to splash out for a full on tube preamp or amp.  Finally I decided on 3 tubes: a Mullard, Telefunken and Radio Technique.  So far the Mullard is my favorite, warm and detailed opened up the sound, creating a great soundstage.
 
With well recorded music it's night and day.  With dynamic music a godsend.  With contemporary Pop, compressed and normalized up the wazoo, it's great but, no offense to all the Drake lovers out there... you're missing out. 
 
So back to the review - 
 
The Bravo Audio unit itself is lovely and well made.  However the design, for someone who wants to roll some tubes, is a little cumbersome.  I took off the top cover (and the cute but useless anti-roll bar) by un screwing the top screws from the front and back plate. 
 
It's now open to the elements but I blow it out with a handy giottos Rocket (used for photo gear) every couple days or so.  I've discarded the standard tube and popped in the Mullard and been amazed at the quality.  It's quiet and lovely and detailed.  Don't use the standard tubes.  Do some research and put in at least another 20-60 smackers to get you some NOS magic.  Though I hear the GE and RCA tubes are fine as well. 
 
A caveat, these older tubes can add a very slight noise to the system.  Depending on what your source is it can be a very soft high end hiss (maybe my power source or cabling isn't up to par, but I forget about it once I'm in the music.)
 
And now, 
Here's the kicker.  I use it as a preamp for my small system.  Going from output to input - Elac b6 speakers, Dayton Audio amp - which is plenty powerful, Blue Wave Audio with Mullard tube (12au7), to Audioengine B1 bluetooth receiver.  I stream Spotify at extreme quality at home.  I'm not a viny collector nor do I want to nor can I afford to spend tens of thousands of dollars on audio gear. 
Yes it's 320kbps but through this system it really changes my listening habits.  I'm adding a bsr equalizer but that's another post.
 
I'm listening right now through a pair of Grado 125e (my 325s are going to get woodied up) and I love the sound.
The highs are clear and the sound feels so present.  Grandbrothers is the artist of my moment, an Instrumental, beat driven, fascinating group out of Frankfurt. 
 
I love that I have some tube action in my ears and I have to say this headphone amp is a fantastic way to get into this!
 
EDIT - after a month of listening I've fell down the rabbit hole.  I've switched to NOS Telefunken tubes ca. 1960 and I've upped my head-fi game to include the GS1000e.  That has a been a revelation.
I had received my mahogany cupped 325e pair back from yew woodworks on Etsy.  Both cans benefit from the smoothing of the tubes.  The details are still there but the fatigue is much less.  Still breaking them all in but very happy.
 
 I'm loving how this system resolves and since I've switched from Spotify to Tidal (yes it definitely helps and the extra money a month is worth it for the sound and the better interface) I've really reaped the benefits.  
 
I've also upgraded my work setup to include a Bravo V2 tube amp, and am breaking in some Akg 553 and waiting for a Massdrop 7xx.  Looking forward to many more months of great audio. 
 
In a nutshell, Bravo with some NOS tubes (find ones you like and throw out or save those stock tubes for a rainy day) are the way to go without breaking the bank.