the Eikon is better than both but not the same signature. It's closer to the HE-500 in that way but a step or two above. The LCD-2F is warmer and has that wall of bass that only planars can give, but the Eikon is far more transparent through out and both male and female vocals shine along with string,woodwind and brass instruments.
I bought another one too so now I'm going to build it and add SB to one then A/B them. I'll keep the one that came out best and sell the other.PS I would suggest picking up a rac 6as7g power tube or 6n13s like http://m.ebay.com/itm/1x-6N13S-Audiophile-Dual-Triode-Tube-Svetlana-6AS7G-ECC230-6080-NOS-Tested-/322444752950?nav=SEARCH . I preferred the 6n13s it had a blacker back ground of the 2 I had. They both have better soundstage and cleaner bass then stock and it's under...
I built a BHC for the Eikon and they sound great paired. The only other headphones I have that are high impedance are the HD6XX and the T90 the Eikon is a good step up from them. It's almost the love child of the two it takes the best of both the transparency and some of the sparkle of the T90 and the warmth and bass from the HD6XX.As for the Crack I liked it over Burson soloist SL and Gustard H10 the only other amps I have on hand. I have yet to add speedball I will in...
I would go with the Ori. They are a the older set and people (I'm one) like them with the TH-X00 the Eikon have not been out that long. Edit:Better mids not as much slam in the bass but just as deep if not deeper treble about the same larger soundstage.
As mandrake said the H10 is a warmer sounding amp, works great with planar headphones of all types.
For on a budget op-amps take a look at 797bz/an for singles and the 823 or LT1364CN8 for dual.