Disclaimer: I have noticed that my approach to headphone evaluation is a little different. Frequency response doesn’t really stand out to me. Even though I’m a musician and I’ve been exploring headphones for a few years now, I still can’t really tell where there are peaks or valleys in the frequency range. Quality and quantity of bass and sub bass I can usually describe, but the rest of the range usually sounds fine to me in most situations. Maybe it’s because I’m a musician that I notice different things and consider aspects other than FR to be more important. I’m about detail, separation, and “presence” or “strength” or “effortlessness” or “completeness” of the sound.
The Focal Elex are the best headphone I personally have listened to. They push all the right buttons, sounding the most natural and musical. They take zero work to listen to: the music is presented in as straightforward a manner as possible, without ever being boring or fatiguing. I just put them on and enjoy the music. As I upgrade my DACs and amps, the Focals match the improvements step by step, proving their scalability. They are revealing, detailed, and satisfying. They are as open a headphone as you will probably ever find, which might be the reason for their musical, effortless nature.
Let’s talk Nighthawks. There’s a reason Audioquest named them Nighthawks. In a word, they are dark. They aren’t the resolving detail monsters that the Elex are, but they aren’t a slouch either. They aren’t my first choice for music where I want to clearly hear every note from every instrument, but for casual listening of more popular stuff, the Hawks can really add an appealing flavor. I guess you could think of it as putting on very slightly out of focus sunglasses. Details are just a little less sharp, but the most noticeable difference is in the overall color of what you are experiencing. I keep them around and use them often just because I like the variety. Also, they are very comfortable. I like the suede pads, their overall weight is good, and the self-adjusting comfort strap is a work of genius.
The Elegias are not a closed back Elex. I think of them as my “luxury closed back” headphones. Putting them on is like getting behind the wheel of a luxury automobile. It’s easy to tune out the world and immerse myself in the music with these cans - a very soothing feeling. Soundwise, I would describe them as accurate, solid, and strong. For overall sound quality - accuracy and strength - I would rate them the best of my three closed backs, the other two being the DT177X and the Meze 99 Neo. They just blow away the two closed backs I’ve sold - TRX-00 Mahogany (too much bass, too muffled) and the Ether CX (the most boring headphone I’ve ever heard).
Finally, a word about cables. It’s common knowledge that the Elegia cables are some of the worst cables ever made. Lots of folks have gripes with the Elex cables too, but I actually like them. So I put the stock Elegia cables in a drawer and just use one of the cables from the Elex, which ships with a 1/4" TRS termination plus an XLR termination, both 6 ft long and compatible with Elegias. I’m not a fan of the Nighthawk cable - like many people, I have found it to be “weird.” My Hart Audio replacement is being made probably as we speak.