In the final, 32d epistle of “Iggeret HaKodesh” the Alter Rebbe speaks about the inner inspiration which comes after reading the Shema and crystallizes into practical expression in this material as the mitzvah of tzedakah:
“an arousal of the love of G-d when reading the Shema, cleaving to Him and surrendering one’s soul at Echad, and [loving G-d] ‘with all [his] wealth,’ in the literal sense.” ( Iggeret HaKodesh, Epistle 32)
The literal sense of the phrase בכל מאדך indeed can be understood as “with all your wealth” (as in Berachot 54a).
Interestingly, there is another, Chassidic interpretation of the phrase בכל מאדך. It is understood to refer to an infinite commitment to G‑dliness which takes a person beyond his individual self.
The Hebrew “meodecha” is broken into two words: “meod” and “shelcha”, that is “your meod”. It indicates that a person is capable of going beyond his own individual limits. The individual efforts in transcendence may differ (what is considered transcendent for one person may be considered limited for another). Nevertheless, even such an increase which goes beyond the person’s ordinary limits is capable of calling forth G‑d’s ultimate transcendence.
From the Rebbe’s explanations:
“And it is through tapping the infinite potential in a Jew’s soul, each individual according to his nature, that we can reveal G‑d’s infinity. This will be reflected in the revelation of “the new [dimensions of the] Torah which will emerge from Me” in the Era of the Redemption, for this will be an infinite dimension of the Torah. Similarly, it is connected with a true “increase in life,” the eternal life of the second period of the Era of the Redemption”… (From the Rebbe’s talk, “Vaetchanan”, 16th Day of Menachem Av, 5751).