You know, if you are concerned about burn marks on the long white resistors, then it's something you don't need to worry about if you add the Speedball upgrade. In making the upgrade you actually remove and discard those resistors!
Another kit I would consider as a second kit would be the Single Ended eXperimenter's (S.E.X.) kit. It's a great headphone amp that can be used with pretty much any headphone, not just the high impedance ones that the Crack plays well with. On top of that, you can add efficient speakers and listen that way. You would be surprised at what a 2 watt amp can do with the right speakers!
Congrats on a nice Crack build! Looks great!
Scott Burgess
BeePre 2, Kaiju, Eros 2, Rega P6, Rega Apollo CD player, Bryston BDA-1 DAC, Bryston BDP-1 streamer, Jager speakers, Mainline and Crack for headphones.