I used the fosi 50x2 and decided I needed a little more power so I upgraded to the 100x2 version with bluetooth. Power 19V. Both the 50x2 and 100x2 will spark if you plug in the back panel, which is scary. If you plug it in first and then plug the power adapter into an outlet, there will be no spark. The 100x2 has separate controls for bass, treble and volume. With 50x2 there is only one volume control. 100x2 has Bluetooth. When I connect my iPhone xs to it via Bluetooth and play through the music app, the audio is terrible. Everything sounds great when playing TV audio via Toslink->RCA via DAC. But when I sync my phone via bluetooth it's so bad. I'll record a video about it later and update my review. For the extra money, it's worth having more power and bass/treble control. But don't buy for Bluetooth. This device costs $77. I have a Nobsound NS-15G PRO CSR8675. It comes with a 19V adapter but I replaced it with a 24V 4.5A adapter I had laying around and it works much better and delivers more power to the speakers.
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