TLDR: These are unbelievable headphones in every way possible, they compete with headphones well above their price and are made with modern listening habits in mind.
The Sennheiser HD 58X Jubilee have rewritten what a $150 headphone could sound like. The release of these headphones will be as monumental to the budget audiophile community as the original release of the Objective2 Amp, maybe even more. These can be driven well using a regular phone (errr, ones with a headphone jack..), so you won't need any additional hardware for really amazing sound, although when paired with a proper dac and amp you will get a little more out of them, but these do not "scale up" the same way the HD 650/6XX will with better and better amps.
The sound remarkably clean throughout the entire spectrum, lows are strong but not boomy, the mids are quite full, and the highs are fairly detailed, but not blurry by any means.
The bass is a strong pronounced feature of these headphones, but not distracting. You definitely won't feel like these don't pack enough bass, but it's not distracting, it's complimentary, very much like the sound of a movie theater, the bass is there but it seamlessly blends in with the rest of the sound. This bass is also very clean and precise, it doesn't linger or get muddy. If anything, maybe a little more sub bass would be nice, but that is purely a personal taste as I also love my TH-X00s. Overall, the bass is a 9/10, this is an exceptional headphone in this category.
The mids are very equivalent to the HD 6XX, vocals are beautiful, both male and female vocals will be exceptionally detailed, you will only be bound by the actual recording quality of the song. The are perhaps on the warmer side, but that is definitely to the benefit of modern music and use cases. Compared the HD 6XX, these will sound like the have a slightly recessed mid, but I believe that will be because the 58X has a stronger lower bass kick.
The highs are the only place where I can detect any room for a little improvement. These are not painfully sharp, and will allow you to have extremely long listening sessions without fatigue, I believe this to be by design. Sure, a little bit of detail is lost compared to the HD 6XX, but not by much. The highs are very pleasant overall but it may disappoint treble enthusiast who may prefer the DT990 sound.
This sound signature is perfect for modern listening habits. Video games are fantastic, great headphones for most games, although they won't give you "footsteps" boost that you'll find in the DT 990, but that's a good thing for most people. Movies are perfect, these have the perfect signature and sound-stage for listening to movies, absolutely perfect. Music will sound great all around, but definitely emphasized on more modern tastes, the extraordinary contained bass keeps these right in between analytical and fun when listening to all genres. Classical and country will benefit the least from this core feature of the headphone, but it's not distracting and will still sound rich and full bodied, but pop rock and rap will definitely benefit from the bass.
I know I made a lot of comparisons to the to the 6XX, but that's honestly what a large number of people will be deciding against, and the HD 650/6XX serves as a great baseline to measure these headphones against. Build quality, these are solid Sennheiser set of headphones, maybe a little better build quality than the 6XX, but we're talking minimal differences, 6XX are midnight blue, these are black.
A lot of people will ask, 58X or 6XX? If you don't have a decent amp, 58X hands down, you'll never be able to get the 6XX sounding as good as these off your phone or motherboard, or even a fairly low power amp. If you do have an amp (think at least a Magni 2), then it depends on what you want more of, deeper more pronounced lows - 58X, more detailed highs and a flatter sound - 6XX, also remember the differences are small and both will have good lows and detailed highs overall. I also have ignored reviewing these against the HD 660 S because I do not own a pair to really compare against, but as you've probably heard, these are really freaking close to the HD 660 S. These do not use the same driver as the HD 660 S, this has been confirmed by Sennheiser, and the foam behind the driver is mostly acoustically transparent, and is meant for extra durability due to the driver being mounted differently.
This entire review is excluding the fact that the initial drop was at $150, which is a ridiculous steal. I think if there is a price increase, it will be to $200, which still makes them a steal, but now you really have to decide between these or the 6XX. They could increase the price of these to pretty insane levels and I would still say they are worth it.