^ This!!! Pro 50 has been the biggest puzzle for me with a love-hate relationship when I first start listening to it. Now, I'm addicted to its sound, and think it has the most organic timbre out of anything I have listened to. A lot of headphones in my collection are bright in the upper mids/treble, which makes them more revealing and exciting, and my brain got adjusted to that signature. So when I start listening to Pro 50, it was too dark for me. They are more on a darker side, but after many hours of listening (and 100hrs of combined burn in and listening) - I started to appreciate more and more how NATURAL it sounds. It's not an artificial sound, it's pure and organic, very ear-friendly. Keep in mind, big part of Westone business is still hearing earpieces, and these guys know how to tune their drivers ;) Now even W40, in comparison to Pro 50, sounds a bit harsh and less realistic at the top end.
Btw, as much as Epic cable is convenient, I would strongly suggest investing into Pure Silver Litz type of cable for Pro 50. Not silver-plated Litz or Pure Copper, but Pure Silver cable. I'm testing Whiplash TWag v3 now and very pleased with it in comparison to Pure Copper (detailed, but still warm/smooth) and even Linum Silver-Plated Litz (very detailed, but too much boost at low end). Pure Silver significantly improves retrieval of details, improves dynamics of the sound, super transparent, and soundstage improvement is very noticeable as well (especially with imaging and positioning of instruments and vocals). Something I discovered with TWag v3, in a few of the songs the decay of panned sounds was too short and the sounds itself were veiled (when using stock OFC Epic cable) - all this specific to hard L/R panned sounds. UM Pro 50 is not a king of sound stage, it's a Pro series for musicians to keep a focus on the music. Well, this Pure Silver cable opens up the soundstage and captures all the details at the edges of it. I'm using hi-res Cayin N6 DAP, so a level of detail retrieval will depend on a quality of your source, but still I'm quite amazed with what I'm hearing after I switched to TWag v3.