Just found a pretty cool spot and haven't seen it posted yet, currently running my barb through it and you can expect 4-6 bars maybe more if you have exp gear.
The spot is in act 3 on Machines of war subsection Destroy the ballistea, when you select it you'll start on the bridge of korsik and the run consists of killing the 500+ mob packs that all attack. This method is fast but not as easy as faceroll zolton kulle unless you have nice gear.
Ill try and post some pics in a few mins showing my route and quest etc.