The Axe-Fx II XL has the same DSP and amp modeling capabilities as the Axe-Fx II Mark II, but offers expanded memory, new I/O ports, and other upgrades detailed below: http://www.premierguitar.com/blogs/5-daily-news/post/20306-fractal-audio-announces-axe-fx-ii-xl Specs: Built-in FASLINK port for connection to MFC-101 Mark III over conventional XLR cables.Dedicated MIDI IN, OUT, and THRU jacks (vs. shared OUT/THRU in the Mark II).Two onboard PEDAL jacks (vs. one in the Mark II).Primary VALUE entry via optical encoder with a lifespan of 1,000,000+ rotations.“Secret Sauce III” instrument input features an even lower noise floor.128 Mb of non-volatile Super-?FLASH memory allows for storage of up to 512 presets and 512 user cabinets with copious reserves for future expansion.Double-capacity preset size allows for expanded functionality including X/Y switching on more blocks and more instances of effects.Built-in backup firmware allows recovery in the event of complications during update.Backward compatibility with Axe-Fx II Mark I/II presets via Axe-Edit software.