A sample pack is a bundle of audio files mapped to the stock instrument slots (kick, snare, hats, etc). Activate a pack and every track that uses a stock id plays YOUR sample instead of the synthesized default — across both decks, every project. Star (★) a pack to make it the default kit, and every new project starts with it loaded.

• Open the Packs tab in the left-pane library (the layered icon).
• Click + New Pack → name it → the per-slot editor opens. 23 stock instrument slots grouped by family (Kicks, Snares, Hats, Toms, Hand, Metal, Other).
• For each slot: drag an audio file from anywhere (Disk tab, Finder, Files app), or click the row to pick. ▶ buttons preview the original and your override.
• Tap ● Activate in the editor — every track using that stock id plays your sample. Tap ★ to make it the default kit.
• DJ mode: each deck can run a different pack simultaneously. Activate from inside each deck's Packs tab.