[defrost]

Wim Mertens has some great piano compositions, although they also tend to sneak in a few strings and voices.

eg:

[1] https://www.youtube.com/watch?v=o77R2TuScWU

[2] https://www.youtube.com/watch?v=pybqjwf8w8s

and then there's improv; The Köln Concert is superb - but not available on youtube w/out subscription.

[3] https://en.wikipedia.org/wiki/The_K%C3%B6ln_Concert