Does the LCD-S20 need an amplifier?

Not necessarily. At 18 ohms and 93 dB/1mW it is easy to drive, so a laptop headphone jack can reach a usable volume. A dedicated amp or dongle DAC still helps with headroom and clean output.

Is the LCD-S20 open-back or closed-back?

It is open-back. Sound leaks out and outside noise comes in, so it suits a quiet room more than a commute or a shared office.

Can I use the LCD-S20 for calls or gaming chat?

No. It has no microphone and no in-line controls, so you would need a separate mic for calls or voice chat.

What is in the box with the LCD-S20?

The headphone comes with a detachable 2.5 m cable ending in a 6.35 mm plug. Check the listing for any adapter or case included.

How does the LCD-S20 compare with other Audeze LCD models?

It is the more affordable entry into Audeze's planar magnetic LCD line, with a 90 mm driver and SLAM motor. Higher LCD models add different magnets, materials and tuning at higher prices.