Has there been any sort of update on this issue, I have the same problem, been troubleshooting for the last two days without any progress. Worth mentioning, at least in my case, Vanilla Launches without issue, but no mod packs will launch on any launcher that I've tried (Technic, AT Launcher, and Curse). I Loaded the mods from the latest "Tekkit Legends" release into a clean install of forge to see the crash report and it seems to be the same issue across all launchers.
http://paste.ubuntu.com/23883291/
Some error is occurring between hitting the "launch" key and the game window opening. If anyone could help it would be greatly appreciated.
(here are the crash reports from the other launchers for reference)
"FTB Departed" http://paste.ubuntu.com/23883280/
"AT Launcher" http://paste.ubuntu.com/23883306/
EDIT: (As of January 23 2017) the issue was the Newest Nvidia Graphics Driver. I downgraded to the December 14 release and the problem no longer persisted