Thanks to @jexby for generously lending me his Mjolnir 2 and Black Widow 1, as well as a conveniently timed ECP Black Diamond purchase on my end with money I shouldn't have spent, I've had some good times sticking phallic-like, gold-plated objects in and out of open holes on these amps and my existing, modded Super 7 just to see what sort of noises I could get them to make. For my initial tests, I used my trusted, modded HD650. When able, I ran balanced in and out, because there's nothing better than sticking three or four separated pokers in the same hole vs. just one poker in one hole, granted the one poker is longer and girthier. As I go about my business over the next week or so, and assuming I have time, I'll update this post with findings with other headphones or other amps thrown into the mix. Format will be more about traits of individual amps with some comparison notes thrown in there. Can always answer specific comparison questions later. I would like to point out that it is often easier to critique a product than compliment, so don't take a lack of compliment to mean I had nothing positive to say in that area. Often, leaving out a critique means that particular area was positive. Eddie Current Black Widow (First Edition) - Awesome tone. Yes, it leans towards the thick, warm, and powerful sounding side of the spectrum. Some may not like this, some will specifically look for this. I like it. Not usually found in solid state land, and one of the few solid state amps I feel doesn't make the HD650 sound lean and strained. - Surprisingly liquid and smooth for solid state. I found it better in this regard than both the Mjolnir 2 and Black Diamond. - Has a bit of bloom to it, sort-of-but-not-exactly like a well-tuned tube amp. Gives a feeling of fleshed out bass and midrange. Downside is that it can muddy or bloat up the sound just a bit, which causes a lack of definition, tautness, and texture in the bass and low-mids. - Good low-end extension. Top-end is a bit rolled compared to the Mjolnir 2 or Black Diamond. - More likely to give you that feeling of engagement without edge than Mjolnir 2 or Black Diamond. Easier to sink in and relax or feel involved. Mjolnir 2 and Black Diamond are less easy going and are more prone to fatigue. - Does not dig as deep with details compared to Mjolnir 2 and Black Diamond, but still holds its own. At first glance, nothing sounds missing, though you can hear that last bit of resolution missing in direct comparisons. - Really powerful sounding. Almost in-your-face, and with a small but 3D stage, not unlike a highly modded Crack. Micro-dynamics can seem a bit compressed at times, but it's still a lively amp. - Overall, a very enjoyable solid state amp. One of my favorites. While it isn't the best in all areas, it's rare to find a solid state amp with such a pleasing tone, dynamic sound, and liquidity without completely suffering in other areas. It isn't necessarily for everyone, but it's certainly a standout, one-of-a-kind solid state amp. Good if you want something like a good tube sound but need solid state for some reason. - Random note: The Black Widow 1 and a highly modded Crack share some other similar traits beyond what I already touched on. Schiit Mjolnir 2 (w/ some sort of Dutch, NOS tubes, I think.) - Not a lot of talk about the Mjolnir 2. Seems it is overlooked in favor of cheaper or pricier amps. I think this is a mistake and does the amp a disservice for those looking for a well-rounded, versatile, readily-available amp under $1K. - First thing I noticed was a sense of quick dynamics. Grip on the low-end is excellent. You can feel the driver snapping back and forth almost instantly, creating a sense of low-end, tactile feedback I hadn't heard quite like that on the HD650. Dynamics on a macro and micro sense were great, though macro trumped micro on this amp. Very powerful sounding amp overall. - Stage is very wide but lacks depth. Think 2D plane for the stage. - Compared to a very neutral, very tight solid state amp, lower end can sound a bit rounded on the Mjolnir 2. This is subtle, however, and easily made up for by the sense of fleshy fullness you get with the Mjolnir 2's lower half. Note that I am splitting hairs. - Not as liquid as the Black Widow or Super 7, but not bad. Not as dry as the Black Diamond. Strikes a nice balance. - A bit hard and bright sounding in the top-most registers. Minor complaint. Note that I did not say it sounded etched or sibilant. - Details, resolution, ability to dig deep, etc. quite impressive. Very competent sounding overall. Is held back when it comes to layering, staging, and separating out items. Sometimes the flat stage gets in the way of other sorts of resolution, i.e. the sort of resolution that requires good layering. - Overall, the only thing holding the Mjolnir 2 back is a wide but flat, 2D stage, and a bit of upper-treble emphasis. Could be that other tubes will alleviate these traits. However, these are very minor complains. In all other regards, the Mjolnir 2 is a very respectable, great sounding amp. I would not fault someone for having this as their end-game amp. It is quick, dynamic, powerful, snappy, technically competent, and strikes a nice tonal balance with some pleasurable tube-like qualities. Almost a best of both worlds sort of sound. Works well with dynamics and planars. ECP Black Diamond - Ignoring sound, certainly the most unique amp of the bunch. Probably harder to obtain than a Black Widow, so maybe not the most useful impressions if you're looking for one to buy. - Very fast sounding. Sharp transients. Laser focused sound compared to the others. Tight from top to bottom, including low-end texture. - Stage is on the smaller side of things, but larger than Black Widow. Has a nice 3D, spherical feel to it. Good sense of air and ambiance, albeit as much as you can get in a smaller stage. Not as in-your-face as Black Widow either, in that the stage takes a step back. - Thanks to the stage and speed of the amp, it sounds very detailed and makes it easy to pick everything out of the music. Very pure sense of clarity that you don't usually get without tubes, but also has its own unique play on it. - Really good micro-dynamics. However, macro-dynamics and a sense of sheer power and authority is definitely a weak spot relative to the other amps. - Good extension from top to bottom, but sounds a bit lean, or perhaps overly neutral. Lacks heft and sustain in lower registers. - Least liquid of the amps. A bit of upper-mid/lower-treble bite. Slightly dry and hard timbre. Upper-treble not as bright as Mjolnir 2 but more so than Black Widow or Super 7. - Overall, probably the least "musical" of the amps. That said, the speed and pure sense of clarity is really something worth hearing. It sounds very different than what you normally get from solid state, nor does it quite sound like tubes either. Clearly the unique design and high quality transformers are doing some good stuff here. I am not sure how best to describe the Black Diamond, really, because I hadn't heard anything quite like it until now (wasn't quite as good as picking these things up when I heard the prototype, and I think the production unit is better FWIW). - Foreshadowing: Seems to respond to and change a noticeable amount with simple mods. Eddie Current Super 7 (Modded) - Fair comparison? Maybe not. Probably the hardest amp to find of the lot, but when they do pop up for around $1K, it's a steal for the sound quality. I mean, seriously, the fact these don't get snatched up immediately is a sign that everyone dropped the ball that looked but didn't buy. Mods on my unit include voltage regulator upgrade to a Belleson unit, TOCOS potentiometer, upgraded wiring for the pot, upgraded caps (Cardas 0.1uf, and CDE motor run 10uf), as well as my own tube preferences. The voltage regulator mod allows me to run the RCA 6BX7 in the driver stage, which I find is a very capable tube and not quite like the usual RCA sound. Big thanks to @MisterRogers for helping me out with this and the Changstar community for posting about S7 cap swapping long ago. This is real TOTL shit here. - The most "grand" sounding amp of the lot. Stage width is about on par with the Mjolnir 2. What the S7 has in addition is an excellent holographic feel to the stage. It mixes the Black Diamond's 3D, layered stage and ambiance with the Black Widows ability to get in your face if needed and throws steroids and sex into the mix to make it even better than the other amps. - Tonally is most similar to the Black Widow, albeit the timbre is even more liquid (most liquid of the bunch), and the bass quality is better (more powerful, tighter, better texture and pitch, etc). - Regarding bass, in general reminds me most of Mjolnir 2, just with a bit more bloom to it. That is, the Mjolnir 2 is a bit tighter and a bit snappier/has slightly more slam, but A) it's not too far off and B) the Mjolnir 2 suffers in other ways the S7 does not. There are also times, like with bass guitar, where despite the S7 being a bit bloomier, you can still pick the bass out more easily due to the more layered sound. S7, you could pick out the bass player jamming along. Mjolnir 2, you could hear the bass player, but that's it, and couldn't hear them as well as the S7. Black Diamond is still the tightest of the lot, if that matters, but had a more clinical feel to it. - S7 seems to keep all the details and resolving power of these amps, if not being a bit better, yet never sounds artificially sharpened, etched, hard, or sibilant. While the Black Diamond had this particular laser focus to the sound, the S7 digs just as deep but sounds incredibly organic doing so. It is hard to fully grasp the amount of organic clarity you can get out of tube amps until you've heard it. - Uncanny ability to let you relax, sit at the edge of your seat in engagement, or analyze all the nuances of your music. However you'd like to listen, the S7 doesn't get in the way. A lot of people are used to "relaxing" or "fatigue free" being coupled with an overly warm or mushy sound, lack of dynamics, loss of clarity, or what have you. S7 will let you relax if you so choose but not because it suffers in other areas. Hell, you can relax and analyze your music at the same time if you want. Weird, right? - Responds well to mods and tube changes. You can make the S7 sound pretty gosh darn nasty and etched if you'd like. You could also make it sound more like mud. Mine would be like an uber-Black Widow with a much better stage, if I had to simplify. Long story short, while all of these amps have their positive traits, S7 is like getting your first taste of a sound without compromises. Other Headphone Notes (Brief, WIP if I can and remember) I'll try to fill this out more as I go along. Since I have the Ether and Ether C in the house now, my thoughts are: I only really like them from the S7. The Mjolnir 2 and Black Diamond exaccerbate either Ether's inherent rough traits. Black Widow is better in this regard but doesn't make them sound as powerful as I'd like and, due to the amp having a small stage, makes the already small, crappy stage on the Ethers sound even worse. S7 is the only cure in my arsenal!