I often play that system seriously loud, and have NEVER had the amp get "switched off," even after several hours at that volume.
Sorry, I am interested in exact data only when testing the amplifier. You "often" (means what?) play music - translated as undefined time, undefined average power value with undefined signal. As I explained, I want the amp to meet the defined specs, not individual undefined conditions based on subjective opinion, not YOUR conditions but repeatable reliably defined test conditions.
TPA3255 may have sophisticated protection circuitry, but the undersized heatsink in a closed too small unvented box is definitely not sophisticated. It is what it is, a cute toy that can bring a lot of fun, but definitely not a serious amplifiers that meets standard specs. Not mentioning the ridiculous 2 x 300W they declare. Not a second it would give that power.