There are some videos at the bottom where it is played. It sounds beautiful. The range is like a normal 88 key piano, no extra keys but what matters is the difference in timbre in the low notes. Your 'regular' piano has what is called an overwound string, a steel string that is covered with one or two layers of copper. This results in a string that sounds less pure. The Alexander piano is special in that it uses no overwound strings, all the bass notes are simply simplex strings at their natural length without added weight to reduce their period of oscillation. It also has a huge soundboard, so presumably it is quite loud, but the main difference is in how the bases sound.
I listened to the Clara Schumann piece and I thought the low notes have a "perfectly tinny" sound, as if they were computer-generated on MATLAB. Or like a harpsichord. I assume that's the difference?
I wouldn't call it tinny, I would call the alternative 'muddy'. It's a much more pure tone than you would get from a 'normal' bass string (which is actually quite a complex piece by itself).
FWIW I've noticed that "rattling" (which I think I hear in the Liszt Funerailles video) in some K-pop videos featuring electronic low bass at the ~40Hz level. I think it might be natural and not an artifact or flaw.
