Daf Yomi Insights - Berachos 8

In 1952 a group of people attempted to break off from Bais Medrash haGadol, a shul in University City, MO and begin a Young Israel minyan. As they did not yet have their own location they rented a place in which "all manner of licentious and frivolous behavior occurred" in order to hold their services for Rosh Hashana and Yom Kippur. The rabbi of Bais Medrash haGadol approached Rav Menachem Zvi Eichenstein who was the official Chief Rabbi of St Louis to prevent this breakaway minyan for two reasons. First of all he argued that they were making an minyan in an inappropriate location, secondly, by taking members away from the existing shul they were causing financial harm to the shul.
Rabbi Eichenstein agreed that it was not right to make a minyan in such a location, but held that the Halacha is in accordance with the Rivash that we encourage there to be more shuls and therefore the existing shul cannot complain about the financial loss due to new competition. Rav Eichenstein then sent the shaila to Rav Moshe Feinstein to see if he concurred. The shaila appears in אגרות משה או"ל א' ל"ב.
With regards to the propriety of davening in such a location, Rav Moshe cites the Gemara Berachos 8 in which we find that Abaya would only daven in the same location where he studied Torah. Rav Moshe cites this as proof that the other activities in the location have an effect of the efficacy of the prayers said there. If a place where one learns Torah is a place where it is good to daven then it follows that a place where despicable activities take place is not an appropriate place for davening as it is despised by Hashem and davening should occur in a place loved by Hashem, e.g. a place where Torah is studied.
According to Tosefos one should daven where he learns even if that means he will daven without a minyan. The Rambam says that it must be with a minyan, but even if there is a smaller crowd where he learns, and the rule is that ברוב עם הדרת מלך, that it is preferable to daven with a larger crowd, davening where he learns takes precedence. Rav Moshe suggests that the argument between Tosefos and the Rambam is dependent on a disagreement in the Gemara as to the source for davening with a group. According to Rebbe Yochanan in the name of Rebbe Shimon bar Yochai the reason is to daven in an עת רצון, a circumstance in which God is likely to accept the prayer. While the Gemara does not explain how that means a minyan Rav Moshe suggests that we learned on Daf 6 that the Schechina is present when ten are present so that must make a minyan qualify as an עת רצון. According to רב אחא we learn it from כביר ולא ימאס, that Hashem will not despise a multitude. From there we learn that the prayer of a multitude is assured that it will be heard and accepted.
Rav Moshe then suggests that according to the first reason what's important is the presence of the Schechina. If you can get the Schechina to arrive, even without a minyan because it is a place of Torah learning, then it is fine, as Tosefos holds. However, according to the second opinion what matters is a crowd, so you must have a minimum crowd of ten or go daven elsewhere.
With regards to the issue of monetary damages Rav Moshe disagreed with Rav Eichenstein. He said that the Rivash was only discussing when a permanent building was being erected to serve as a new shul that is a Mitzvah and the builders cannot be held responsible for any financial harm to the existing shul. However, in this case where they wish to break off and daven in a despicable and hated place there is no Mitzvah and the Rivash would agree that the existing shul can prevent them both because there is no need to separate and because it is causing them financial harm.
This is not the entirety of the Teshuva, I only wrote the main points.
P.S. in response to some questions I received about the venue to which Rav Moshe was referring I wanted to share the following:

I spent the years 1979-1984 in St Louis. Around the corner from Bais Medrash HaGadol was an adult theater. I initially assumed this was the location in question. However, after doing some research last night I found that even though the theater opened in 1937 it did not become an adult theater until 1974 (it was subsequently found to be owned by a number of Catholic charities and forced to change the type of movies it showed. It did not last long after that.)

A glance at the shul website shows that when they first opened they met in a variety of places such as VFW halls and any place that would allow them to not pay rent. That led me to another theory.

Around the corner in another direction was a sleazy bar with a bowling alley on the second story. It was off limits to us Yeshiva Bachurim however some Pacman and Centipede addicts used to sneak off there. The nickname for the bar was "the shul." I never knew why it had that nickname and I wonder now if the Young Israel davened there at one point and if it was possibly the target of this teshuva.