hf-seeker I made disload check with 1,0 A until 9 V.The first check reached 2,323 Ah, the second check (after repeated reloading) reached 2,513 Ah. The specification 8000 mAh probably refers to the addition of the capacity of the three cells.

hf-seeker Yes it is a bad product because of the terrible loudspeaker. Give the review 4 - 5 stars for it to appear ;-)

hf-seeker With 3 NiMH cells I heard radio and measured the power consumption of 25 mA. In stand by only 18 μA.

hf-seeker You can use NiMH-cells, works fine. You should power by USB, if you change batteries, otherwise the settings will be lost.

hf-seeker The Bluetooth antenna is already integrated. The housing must not be shielded.

hf-seeker The Datasheet of TPA3118 will help you. at 12v-supply: 4 Ohm - 2x about 20W 8 Ohm - 2x abaut 11W Minimum load 3,2 Ohm.

hf-seeker You should put in 18650 Li-Ion Batteries (have max 4.2V full-load voltage). There must be a load-circuit inside between USB and Battery/Lamp.