Not sure the BHC will even drive the LCD-4… planars and tube amps require specific types of pairings to get good sound out of it.
The Crack is OTL design right? Maybe someone tried it but I doubt the match.
Do you have access to Cayin amps where you live?
Maybe using aliexpress i can get my hands on a Cayin but its a gamble… Which Cayin do you have in mind?
I have read on head-fi of one guy who owns a Viva Egoista and said the BHC is also awesome for the LCD-4, but that is just one opinion.
The Quicksilver drives the LCD-4 perfectly but it does not deliver much of a tube sound, that is why i am thinking OTL.
I have a BHC and tried a few times with an LCD-X and it was not good experience. I doubt it will be a good match with LCD-4 either. Not saying this generalizes to all OTLs though
I was in your shoes a little while ago trying to get an otl that would drive a heavier planar. It just doesnt work well with OTL in most scenarios as it most likely needs a high end / overkill amp design to get the headphones cooking the way they should. I did not like my less efficient planars on the BHC or RNHP.
I did have great success, and it seems you have too, with SET/transformer coupled tube amps. You can look at something that has a different flavor and is more “tubey” in general or depending on the tubes you have now, see if you can nudge the way you want with some tubes.
Maybe someone can offer a differing opinion but the most “tubey” like amplifier that will drive those type of headphones very well ie. Planar HP’s is a decware taboo mark 3 or mark4. The sound is “old school” tube like with a very enhanced midrange depending on your tube roll. Decware knows how to ship international and if Brazil is a nation they have experience with you can get a your amp through them with minimal hassle. 
It may take 2 years or more but it does fit your desires.
Good luck.
The LCD4 is a bit unique being a planar with very high impedance, so you might get away with an OTL amp. To put it in perspective the average OTL amp using a Cathode Follower like the Crack has an output impedance of 60-100+ Ohms. And they usually can’t deliver a lot of current.
I wouldn’t think the crack is a good option to drive it.
Feliks amps might work, but you’d want to get confirmation from someone who’s tried it.
Something like an SW51+ might work it’s going to be about 20-30 Ohms on it’s output, but it’s a step down from the quicksilver in technicalities.
Outside of that you’re in $2K tube amp territory, and my recommendation is if you go there wait and go to the 3K range.
There is more to “tube sound”, by which I assume you mean (richly presented midrange/warmth that many higher quality tube amps just don’t have) than impedance, transformer amps with taps designed for higher output impedances will have more body, but there is more to it in the design than that. The bypass capacitor on the cathode resistor in effect changes local feedback, and selecting the size, can emphasize certain frequencies while presenting more linearity in others.
Tetrodes and Pentodes in ultralinear or pentode strapped configurations will generally be dryer than triodes, or triode strapped tetrodes/pentodes.
In transformer based amps the transformer limits bandwidth, and can have as much impact on the sound as the tube do.
Even with the simplicity of tube amps, the designer has a lot of control.
FWIW Mike at Quicksilver has usually targeted the dryer more linear presentation, I have a pair of his older M135 Monos, and they skew very much the same way.
@luizgarcia I have tried the LCD-4 via an OTL, a BHC to be specific. While the general rule is planar and OTL is a no go zone, in the case of the LCD-4 given its 200 ohm and 97 db/mW ratings works in its favor. It is nowhere near the rest of the Audeze line up in specs, and definitely an outlier as @Polygonhell already alluded to above.
In short it worked fine, it did require cranking up the volume a bit more than say with a 300 ohm Sennheiser but that is a different driver type and also ohm/sensitivity ratings. So while other LCD models like the X, 3, or 5 would be piss poor matches that does not necessarily translate over to the LCD-4. Maybe if you can import a used Amp&Sound that does not break the bank? That would give you that gooey tube sound, though the cost of a BHC is a hell of a lot better.
Nice, so you are the second person to confirm the BHC is viable (even if not ideal)! Did you think it is a good pairing though?
If that was my only amp I would look for a Tung Sol 7236 power tube, input tube could be any of the usual suspects. I say that as I feel the LCD-4 already has a warmer tilt at the expense of treble extension. An OTL may emphasize that more given the dampening effect of the output impedance.
It will not be as fast as a dynamic driver, likely to be less detailed, and will be a laid back combo.
Would that pairing line up with your preferences?
Possibly, i do EQ my LCD-4 so treble extension is not an issue. I don’t want it to sound “better” than it does on the OOR or the Quicksilver, what i am looking for is a more tubey sound for it in cases where i am already dealing with an album which is not well recorded, so losing a bit of detail and dynamics would not be terrible.
Thanks for your input, very helpful!
Fooled around last night with the Audeze presets in Roon. Enabled the LCD-X and took a listen. A couple of my tracks was all it took to take it off and not look back. It completely flattened the stage, felt limp lacking energy, like a succulent plant telling you it needs water. Just beginning to look mushy when the leaves are supposed to be firm and have little give.
Anyway, not sure what it’s all about but it sucked the life out of the chain.
PC > DDC > BF2 > RNHP > LCD-X. Did I do something wrong? What am I missing? Or perhaps this is designed to “improve” a generic chain not something with good synergy? IDK but this wasn’t a case of not being impressed, it was more like yuck.
That Audeze EQ was designed for professionals mixing and such to give them consistent results, not necessarily because it sounds good. 
Personally I never cared much for it on any of their HP models.
Now if you were collaborating with someone across the country and you both wanted to hear something you were working on pretty close to the same, as long as you are using same or similar kit and that EQ you can collaborate with confidence. At least that is the story I understood behind the development of their EQ.
That would make sense given my experience.
The presents – which supposedly are the same as the Reveal plug-in – reduce the forward nature and aggressiveness of the upper mids to me. If you like the stock sound, then I could see the perception that the presets neuter the Audeze “house sound.”
I far prefer the sound of my LCD-X 2021 with the Reveal preset. Makes the can more well-rounded, as the “in your face” upper mids of the stock sound bother me.
Depending on if it is a newer or older X it will need eq in varying amounts, with the newer ones needing less nudging.
If it is on PC try the PEACE plug in and putting in your own EQ. It should lose too much. I based mine off the headphones .com eq settings.
Yeah, it’s the 2021 version. Honestly it was just a try and see how it all worked. It’s an entire portion of Roon that I don’t take advantage of at all the whole DSP thing. I’m fine with that. I’d heard some may people say it changed their chain I was just curious.
I need to order a quality balanced cable for the lcd24 (yggy+v550), I’m thinking Norne cables (don’t want to go above 500$).
I like their new models, Drausk V2 (18awg copper) and Skollvar V2 (19awg copper silver fusion).
The original audeze cable is copper silver so is it true if I want to enhance that sound I go Skollvar and if I want to lean warmer and richer I go Drausk?
I have a couple of Trevor at Nornes cables, I like them, and the build quality is excellent but expect to wait for the cables.
Generally big copper cables will have more prevalent bass, silver ones can tend to be brighter, but it’s not always true.
If you do go Norne, I’d email Trevor first and get an estimate on lead time, then follow up as soon as that estimate inevitably expires.
have you considered Audeze’s premium cable? I liked it when it shipped with my LCD-5.
Did they release a black and gold version of their premium cable before? Currently its black and white.