What does clipping sound like?

I have been wondering if the break up distortion I hear with my 60 watt tube amps is because I have insufficient power for my 91db 6 ohm minimal speakers. I do question if that rating of my speakers is correct.
When the music swells, I get break up sound. It is not on low notes or high volume. I do wonder how my speakers would perform with a lot more power. I have always thought that any speaker likes more power.