Looked like a really fun, unique event. So, what is harp like live at close quarters? I find it can disappear or sound a bit diffuse in concert halls.
I am not a harp player but one lived in the room above me during school days. Sometimes I helped her load it into her car with front seat removed. Harps are big and heavy instruments. I also heard and watched her practice.
The sound of the harp is largely the sound of plucked strings blooming into the air.
Strings vary in length, thickness and material, and tune to proper pitch.
A concert harp has the broadest frequency range of any concert instrument except the piano. Roughly 6-1/2 octaves, so its sound can be much more than the etheral high notes people often associate to it.
It is plucked with the fingers or finger nails, often using two hands at once - harpists have strong usually calloused hands and fingers. Multiple strings can be plucked at the same time. The harpist can let the sound vibrate/bloom into the air or damp the strings to lessen or quiesce the sound, thus controlling articulation and note length.
The strings are in the open air, the harp has no resonating chamber to amplify sound but it does have a soundboard into which the strings send vibrations. Different soundboards shape the timbre, mostly deeper or thinner. Some harps have pedals that allow some strings to be stretched which causes a change in pitch.
Absent amplification, the harpist must work with any accompanists to keep their sound in balance. In an orchestra the harpist often sits at or near the front frequently on the left edge with the 3rd violins. In a living room setting I'd expect its sound to be full, harmonically rich, sweeping or precise (think pizzacato and staccato) according to the music at hand.
Try anything by Marissa Robles.