With nearly 150 hours of serious listening (as opposed to frivolous listening?) through LCD-3s with Norse Audio Norn cable and via Bifrost, I'm still entranced with this amp. That doesn't mean it's perfect.
When I first substituted it for the Lyr, some music sounded less full, especially in the mids. This has become so much less marked as to be no longer noticable. Either the amp has burned in, my ears have adjusted, or quite probably a bit of both. And while I can understand how some folks would find it strident, I don't think that's the amp. On a number of very familiar recordings I've noticed harshness in piano notes, glassy vocals or strings getting edgy. But by no means on all music; some, indeed most, recordings with sharp sounds are just exhilarating without being tooth-gritting.
The Mjolnir does not play nice. This is Thor's frigging hammer after all (or should that be Frigga?) [Of all the hammers I own, I've never thought of naming one. Hmmm, I dub thee Thumbcrusher the Malevolent. Maybe not...] This thing is as revealing as Biden's gaffes and as merciless as a judge at the Nuremburg trials. If there's any unpleasantness on the recording, the Mjolnir won't sugar coat things. Not sure whether it's Schiit's voicing decisions, a consequence of the circlotron design or just solid state as opposed to tubes; although my late and unlamented Violectric wasn't so brusque, at least not as I remember it.
What the Mjolnir does well, it does enthrallingly well. Tectonic bass, more detail than a forensic audit, low noise floor, jumps like a startled acrobat. Not that all the detail doesn't carry a small price - take Tori Amos doing "Yes, Anastasia" which is her at the piano with occasional orchestral interludes. Not only is every breath as if she's doing it right into your ear (not neccessarily a bad thing, granted) but there are noises like she's squirming around on the bench. I almost want to tell her to sit still. And while she certainly wasn't wearing hiking boots to work the pedals, that's what it sounds like. And though you would guess the orchestra was recorded seperately, the Mjolnir makes it almost distractingly obvious. Not that this is bad, really, just something to be aware of.
And if you're a cable skeptic, do not buy this amp. Especially don't buy it then borrow a few sets of high-zoot cables and power cords and do some careful listening. Just stay with your comfortable preconceptions. I just switched power conditioners and...you don't want to know. These things make no difference, right? OTOH, if I was doing studio mixing, this would be a must-hear as an analytical tool. If you seek a gemutlich listening experience, you may want to shop elsewhere. But if you prefer the roller coster to the carousel, the Mjolnir is the proverbial E ticket.