The NS-01G MAX is a revolutionary digital amplifier that packs a MAX 100W x 2 output into an ultra-compact body just 78mm wide. It uses the TPA3221 chip to drive 4Ω passive speakers and wirelessly plays music from your smartphone via Bluetooth 5.0. The PRE OUT terminal allows you to connect a subwoofer or external amplifier, enabling you to build a 2.1ch system. I purchased it on December 30th and used it twice. As the reviews say, the sound quality is generally good and it's very cost-effective, but I'm selling it because it doesn't quite match my preferred sound.