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 last year  

They are extremely cheap, between 2 and 3 US dollars. I hope it can last a few years. I will be updating the performance of the board over time in the comments.

Thanks for comment

 last year  

No problem, those type of items are always expensive around here

 last year  

I'm sorry, I'll do my best to post an upcoming video of making a similar amplifier with recycled electronic components.
Happy day!

 last year  

That's so cool to hear