Tom Dunn opened the scoring in the first minute, while Paul Grant, Anthony Watson and Tom Homer all crossed to wrap up a bonus point by half-time.
Six further tries followed, with Grant and Watson each getting their second, before Rhys Priestland, Zach Mercer, Ben Tapuai and Ross Batty all crossed.
Mosese Ratuvou scored the French side's only try of the game.
Bath's comprehensive victory means they finish top of Pool Four.
And their superior points difference over Pool Three winners Brive, who also finished with 23 points, means they pipped the French side - their likely opponents in the last eight - to a home quarter-final.
Bath: Homer; Rokoduguni, Joseph, Fruean, Watson; Ford (co-capt), Fotuali'i; Catt, Dunn, Palma-Newport, Ewels, Stooke, Mercer, Louw (co-capt), Grant.
Replacements: Batty, Obano, Knight, Charteris, Mercer, Cook, Priestland, Tapuai.
Pau: Buros; Lestremeau, Fumat, Dupouy, Ratuvou; Fajardo, Moa Teutau; Hurou, Lespiaucq Brettes Sclavi, Pesenti, Ramsay, Habel Kuffner, Dougall, Butler (capt).
Replacements: Boundjema, Jacquot, Tierney, Tutaia, Daubagna, Dupichot, Malie, Bernad.
Sin-bin: Habel Kuffner (36)
Ref: Ben Whitehouse
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Bath secured a home European Challenge Cup quarter-final with 10-try thrashing of Pau at The Rec.