One marked difference between Chabad and most other Chasidic groups is that Lubavitch Chasidim, and their Rebbes, are known to pray quietly. However, Passover Seder night is a striking exception.

One year, a number of chasidim who had the honor to participate at the Seder table of the Rebbe Shmuel Shneersohn (Lubavitcher Rebbe #4: 1834-1882) were sitting there in awe and with great respect in the rebbe’s presence, as you would expect. As a result, they were each reading the Hagaddah [text for Passover night] quietly, not wishing to call attention to themselves. The Rebbe instructed them that the Hagaddah is supposed to be recited loudly and that they should do so.

...a number of chasidim...were sitting there in awe and with great respect in the rebbe’s presence...

The Rebbe Yosef-Yitzchak Shneersohn (Lubavitcher Rebbe #6: 1880-1950) also would instruct everyone at his Seder table to read the Hagaddah in a loud voice, even when he himself was no longer able to do so, as a result of suffering a stroke.

The Rebbe Menachem-Mendel Shneerson of our generation (Lubavitcher Rebbe #7: 1902-1994) would himself not read the Hagaddah loudly at his Seder table, but he always appointed one of the guests to be the official reader and to do so in a loud voice, quoting the Arizal (below) for insights into this custom.

In addition to many other Chasidic Rebbes, great Torah authorities who insisted that the Hagaddah be read loudly include the Ritba (1250-1330), The Maharshal (1510-1574), and the Chatam Sofer (1762-1839).

The holy Ari of Tsfat (1534-1572), greatest of the Kabbalists, said that the Hagaddah should be recited loudly, with great joy and with proper focus and intention.

Indeed, it is written in the Zohar that whoever retells the story of the Exodus from Egypt and celebrates it joyfully will merit being joyous in the World to Come together with the Divine Presence.

[Translated-adapted-supplemented from "Otzar Minhagei Chabad" by Rabbi Yehoshua Moonshine, pp. 154-155 (and inspired by Lema'an Yishme'u #93).]