I will wait to give a full review myself however I agree with most things you've said
I do think this Headphone should be in everyone's arsenal and at the price why not ,
So since you can not go to Amazon and buy these if another Drop comes up at Massdrop I will buy another just in case the Dog eats these

@turbomustang84 I look forward to your review too. As mentioned in mine I'm not living the best "audiophile" life here, so it'd be great to see how the HD58x scale up

My HD6XX sounds dead next to the HD58X--almost congested and veiled. Seriously. The 58X reminds me of my Beyerdynamics T5p.2. (which is similar to your Grado comparison) with Fantastic clarity and presence. It's a WINNER! And yes it sounds fantastic right out of my laptop....amazing out of my iDSD Micro Black Label w/iPurifier2 and iGalvanic3.0. Pull the trigger next chance you get!!!!!!!!!!!!!!!!!

Great review and I agree with everything you said. I also own 6XX (650) and it's hard telling them apart besides the bass. It's crazy that I can run these on my iPhone X with Dragonfly Red, and it sounds incredible. Sometimes at home, I'll plug them in my phone, and not my $1600 receiver, and not notice a difference besides volume output. The 58X is part of the 6XX family as stated by Sennheiser and Massdrop. It's actually using same driver size as the 660S.

I really don't like my HD58X, has no soundstage. I still prefer my $55 Philips SHP-9500 with HM5 pleather earpads. The only thing better on HD58X is the bass, and only barely.

Would love to know how it stacks up to the original 580s, both jubilee and precision. I've had the 580 precision for over 10 years and have had no real reason to upgrade. Wonder if the 58X is the one...

@Condocondor I think my comparison between the HD58x and HD6xx will have the same results, but still I like the HD6xx a lot for what it is - (almost) veiled. The HD6xx is my go-to cans for "romantic" music.
Also great choice of the IDSD. The iDSD"s colder sound sig matches perfectly with Senneheiser's HD6 line, I think.

@Megazine Thanks for the compliment. I'm also afraid that my HD58x and HD6xx will sound too much alike - I'm away from home and have not tried them on the same amp/DAC yet. If so I'm afraid I'd have to sell one of the 2.