Alcohol & Chassidus - Some More Sources
Excerpt from a sicha of the Frierdiker Rebbe:
Mashkeh itself should be out of the question for Chassidim. It's surprising how Chassidim have anything to do with mashkeh. Chassidus is intellect, and even middos Chassidus have to be guided by intellect… So, why do Chassidim drink mashkeh? The main point of Chassidus is being on guard (against undesirable practices)… and particularly mashkeh - according to Kabbalah, one has to be especially careful about wine. The Alshich writes, success in one's studies depends upon three things, and one of them is delicate foods. Especially for the study of Kabbalah, for which one of the ways to prepare oneself is to avoid drinking wine. There was a time when Chassidim were told not to make kiddush on wine but one challos.
(from the Sicha of Yud-Tes Kislev, 5691 - 1930: Likkutei Dibburim IV, page 1438)
Excerpt from the teachings of the Lubavitcher Rebbe:
Some think that by drinking they help the Divine soul predominate over the animal soul. The truth is just the opposite; it causes the animal soul to predominate over the Divine soul.
(from the sicha of Shavuous 5728 - 1968)
Concerning what you write about mashkeh…, in my opinion there are two reasons why the situation has changed since the time when considerable drinking of mashkeh was a widespread practice:
a) Because, through the abundance of easier Maamorim (Chassidic philosophical discourses) and Sichos (transcripts of public addresses) on themes that explain and enable one to understand Chassidic concepts, the potential has already been given for Anash (members of the Lubavitch community) to impress their audience with no need for them to imbibe much mashkeh, so that even a little is sufficient.
b) Because, particularly in recent years, it is demanded upon us with added emphasis to spread the wellsprings of Chassidus outwards, and drinking much mashkeh is likely to disturb this considerably. It didn't matter as much when spreading Chassidus was confined to just within the limits of Chassidism and Anash.
In connection with the first reason, I support myself with what I once heard from my father-in-law, the Rebbe, in Riga. He said, "I am at present just as I would be after taking a little mashkeh" - by at present meaning not just at that time but all through the years since he had started taking less mashkeh.
Indeed the ostensible reason was because the doctors had ordered him to take less mashkeh. However, it is obvious that this was only the ostensible reason, which is why it was accepted as such by Chitzonim (those who perceive only the ostensible and irrelevant), but not among Anash who know that Chassidus demands Pnimius (perceiving inner intention). They realized this certainly also a lesson for us on this subject in general - for according to the rule that "the body follows the head," the Chassidim follow our leader, my father-in-law, the Rebbe. Since he said he is now as he would be after taking a little mashkeh, this gives us an instruction to all the Chassidim and it gives them the ability to be at this level.
In the course of my conversation with…, I specifically told him that this is not, G-d forbid, any sort of prohibition or command about not drinking mashkeh, and also does not mean complete abstinence. It is only what seems to me the difference between the effect of a farbrengen with little mashkeh and the extent that the participants go beyond all proportion.
(Letter - Igros Kodesh, Volume VII, page 58)
Source: N'Shei Chabad Newsletter