BRZHIFI 6J3 F5 Tube Preamplifier Bluetooth 5.0 Lossless Player Headphone

Yes, it can.

The temperature is normal and not too high. The hottest part is the tube itself—it's not scorching, but avoid touching it to prevent burns.

Yes, you can. I have over 100 songs in WAV format on my USB drive, and the sound quality is quite good.

It offers great value for the price. It’s just as good as a $200 DAC, and the design is sleek with excellent build quality.

Yes, you can replace it with the following models: 6J5, 6J3, 6J1, 6K4, 6AH5, 6AN5, etc.