Comment by yifanl

It's quite hollow and plasticky on the inside. This is not a bad thing nor a mark of cheapness, but it sounds very roomy and echo-y for a keyboard, so if you like the sound of the clacking on a keyboard, it's quite amplified by the board.

I wasn't around to use an actual C64 to compare the sound against that, but I suspect it's an intentional choice as a retro keyboard to mark itself apart from the foamy modern keyboards that tend to dampen the keyboard.