I'm with you on all of that, as I've been using the Emotiva > LCD-2 without resistors for about a month now, without issues. I am not, however, completely satisfied with the Emotiva itself being a bit bright for my tastes, even with the shelved highs of the LCD-2, and a wee bit harsh, too.
I've been running the Decware ZSTAGE tube buffer to take the edge off the treble, currently using an NOS Siemens 12AU7, having tried rolling several tubes already. The ZSTAGE is about as transparent a piece of tube gear as anyone could hope for, beyond the distortion inherent to the tube itself, of course. Thus, I'm able to warm and soften the treble with the right tube, but it comes with slightly diminished detail - which hurts those low level signals that help imaging. The even order distortion of tubes may be more palatable than odd-order distortion, but it's distortion just the same.
Another aspect of using the ZSTAGE, which is essentially a triode pre-amp with a single set of inputs and outputs, is that I can attenuate the signal coming from the DAC section of my DACmini CX, to force the Emotiva to stretch its legs. I can say that without changing tubes, but rather by just turning down the gain of the signal coming into the Emotiva, while moving the Emotiva's volume control from up from about 8:30 to 11:30, the SPL at the headphones remains the same, but the Emotiva sounds better - with more body and fullness from the waist down, so to speak. The mids, lower mids and bass get more energy (as if to reduce the energy of the treble region). It's not subtle, but it's not a complete "cure," either.
Hoping not to bore anyone here, but as an aside, Steve Deckert (of Decware), offers a less expensive tube buffer, called the ZBOX, which offers only attenuation, from not quite unity gain, down to zero, where, depending on the tube, the ZSTAGE adds the ability to increase gain by as much as 5 dB above unity. His literature suggests that by attenuating the signal going into an amp, you can reduce both the fullness and the dynamics (think saturation and contrast) heard at the speakers or headphones and, conversely, by increasing the gain, above unity (above the 2V rms that comes from my DAC, for example), you can actually increase the fullness and dynamics.
In an email discussion I had with Jan Meier (of Meier Audio) about the impact of variable input gain to an amp, he said that its effectiveness will vary depending on the design of the amp. I've since become convinced that this technique works best with OTL amps (from research, not from personal experience.) I know that this effect is somewhere between placebo and negligible with the Emotiva a-100 Mini-X.
Thus, I'm not losing any fullness or dynamics (saturation or contrast) by attenuating the input gain to the Emotiva. Instead, I'm just getting a favorable shift to the frequency response (to the color balance) as the bass and mids improve with the Emotiva operating in the middle of its power output range (11:30 on the volume control), rather than idling along (at 8:30).
Following this line of reasoning a bit farther, I've also inserted a pair of Harrison Labs 6 dB, inline attenuators at the inputs of the ZSTAGE. This forces the Emotiva's volume control to go up to about 12:30, to maintain the same SPL at the headphones heard without the attenuators. But, for the record, I can't really detect any additional improvement in bass or mid energy, relative to that had by using nearly the maximum possible attenuation via the ZSTAGE volume control In fact, to get the Emotiva volume control to go from 8:30 to 11:30, with the LCD-2, I'm having to run the ZSTAGE volume as low as it can go without causing a channel imbalance - which happens right before it forces silence. Thus, it required a lot of attenuation at the ZSTAGE (a lot more than that had with the 6 dB Harrison Labs attenuators) to get the color shift I'm enjoying with the Emotiva volume moved from 8:30 to 11:30.
OK, writing a book here, I suppose - sorry! But I'll finish by saying that I ordered The Canopener resistor box purely as roll-of-the-dice experiment to see if it can make any aesthetic improvements to the sound, whatsoever.
To put all this into perspective, given that it must sound as if I'm really displeased with the Emotiva... I've sold my Burson Soloist, thanks to this rig - it was just too laid back and lifeless for my tastes. I really love the dynamics and bass control that come with 8Wpc into 50-Ohms, and the clarity while using the Decware ZSTAGE is still superb overall - much better than that of a Schiit Lyr I borrowed from a friend for 30 days. In my opinion, this is the best desktop rig I've ever had, but there's always room for improvement.
Maybe I'll mount some curb feelers next!
I am not trying to be a salesperson for Jan at TBI, but I wonder if you tried out the Millenia amp whether that would solve the issues you are having. You may need a resistor box, like Gary used. Maybe he could sell you one of his, I think he may have an extra one. I am only saying that because Gary had such a great experience with the Millenia with his LCD-3 headphones. Of course, we can play around with all sorts of things in the audio chain to try and get the sound we prefer......nothing wrong with that, if the end result is to our liking. But, just a suggestion. The experience you are having with the Emotiva appears to be a common one, so it sounds like much of what you are doing is compensating for that amp. Anyway, just my two cents, which was not asked for!