I'm trying to decide between a Schiit Vahalla 2 in about ten days or the Liquid Carbon X in March. My primary headphone at the moment is the Sennheiser HD 700 and I have a 6XX coming from Massdrop at Christmas. (I also occasionally use the Hifiman 400i, but with a Magni 2U instead of the LD MKIII.) All my research indicates that the Valhalla 2 should work well with both Sennheisers (and not so much with the 400i). If anyone has any impressions of the Liquid Carbon with these cans, I'd appreciate it.
I can't join the drop until I get a direct deposit on Wednesday morning, so this question could be moot by midweek. I was also seriously considering the Jotunheim, but Schiit tells me that I could not benefit from the increased power of its XLR output if I continue to use the unbalanced Mimby as my DAC, as I intend. Because of its different topology, the LC will output a balanced signal even from a DAC connected to its RCA inputs, so I can take advantage of the extra power of the XLR output. As long as I spring for balanced cables of course.
I can offer my opinion here as I currently own the HD700, Liquid Carbon 2, and the original Valhalla.
Both amps are great, but very different. The LC2 really does require a balanced cable to sound its best, so if you are leaning this way, the cable is a must. My current headphones include Elear, HD700 and T1. My favorite combo is the Elear from the LC2 balanced. Very close second is the HD700 from the Valhalla. The Valhalla really brings out the low end and adds some air to the sound. The Elear however gets overly boomy with the Valhalla, but is very controlled with LC2. The HD700 is a little thin on the LC2 but still sounds decent (I do not have a balanced cable for this) but comes very close to the Elear/LC2 combo when plugged into the Valhalla. The T1 is similar to the HD700 in relation to the amps but is a bit brighter headphone overall.
If I was auditioning these amps with the HD700, I would favor the Valhalla. my 2 cents YMMV.