Finished the Crack up today. Measurements checked out and it fired up without issue. It sounds much nicer with the HD650s than the SEX, just my opinion. It's a fuller, bigger, warmer sound. Really quiet so far too. This is my fifth Bottlehead kit (Foreplay 2, Seduction, SEX, Kaiju, Crack) and it was a lot of fun to build. Currently this is my headphone rig area I move to when it's too late to play the stereo upstairs. I am using Roon and streaming from an Innuos Zen streamer upstairs to a Cambridge Audio DAC/Roon endpoint attached to the Crack.