HeadAmp GS-X Mk2 is what I would get if I had a balanced DAC, and the new GS-X Mini is what I would get with a single endes DAC (which is extremely similar to what I used with the LCD-4). They are as good as it gets from a techniloopcal perspective, and as a bonus also from an aesthetics perspective.
The Gilmore Lite Mark 2 (GS-X Mini) is a purely awesome amplifier. Put that behind a Hugo 2, and that combo will put many a full sized dac / amp to shame. Although it may not fully drive LCD-4 to its potential, it makes LCD4z just sing. And LCDi4 too.