Once you get the headphones, review DAC's and AMP's. Personally I went with a 4 stage (total 8 amp stages for 2 channels) Violetric V281 as it had great reviews and it matched high resolution DAC's. When I reviewed DAC's I found the AMP to support extremely high resolution dac like Hegel HD30 and reproduced the crisp attacky part of the DAC to a level where it wasnt musical anymore. Then I reviwed Schiit Yggdrasil, and it supported that too very nicely. I landed on Yggdrasil as it was more musical and not so extreme attack on instruments still high resolution that makes LCD4 shine, and what a instrument separation Yggdrasil has. In fact the V281 is so good that when I connect my Tascam UH7000 unit as a dac, I can hear a soundstage a little messy and blurry bass reproduction, and when I connect the Oppo HA-1 DAC part I can hear the Sabre chip being bright in upper medium frequency range with less bass.
I read on GS-X website that their amps says only power consumption 15w, but not how much it can provide per channel per level of resistance. The LCD4 is 200 ohms, and requires power. Where LCD3 needs 11-12o clock on volume, the LCD4 needs 3-4o clock, and on some amp's like the V281 the signal is getting warmer and less edgy when volume knob is rised too high. So some amps like V281 has a gain function to increase the signal gain with steps +6 and +12 desibel before signal goes to the amp's, and this takes the volume knob back down to 10-11o clock for most of my listening.
Just bring your headphones to different stores and review combo's, and ask for loaner units home. Its fair to say ordering V281 blind from Lake-people being a pure analogue amp, is a safe bet, doubt you will be negatively surprised, but the DAC is very important to review before purchase, it has more to say than anything. Even on my Sennheiser Momentum 2 with cable I can clearly hear difference between high end dac's.