The dictionary defines Palpable as "so intense as to be almost touched or felt" and it's a great word to describe that which sometimes eludes us in our stereo systems; but elicits ecstasy when we find it.
Evaluating music, equipment, or tweaks by listening involves many different parameters and a great deal of focus. Listeners who regularly gauge the quality of sound have a dizzying array of benchmarks to judge: frequency response, timing, placement, soundstage, depth and size, and all require concentration to sort them; save one.
You cannot have palpable sound when things are wrong in the reproduction chain. When I hear sound I can reach out and touch, no deliberation is needed; this one quality sums all others.
The next time you listen, close your eyes and try and imagine the musicians in the room with you. Can you reach out and touch them?