Agile Partners has updated its AmpKit guitar effects and recording app for iOS adding Retina Display support for the new iPad along with an expanded array of gear available for purchase in the in-app Gear Store. With AmpKit 1.3, bass players can now purchase a full-featured bass amp and cabinet modeled after the Trace Elliot 1215 combo that includes features from the real Trace Elliot amps such as switchable valve (tube) drive and signature Pre Shape…