Complex sentence: Even though tenants should have known that the noise level in this district (and in downtown Toronto in general) could cause a problem for them, many nightclubs have been pressured to minimize the noise; however, it is almost impossible to stop the clamour.
Split into simpler sentences: Even though tenants should have known that the noise level in this district (and in downtown Toronto in general) could cause a problem for them. Many nightclubs have been pressured to minimize the noise; however, it is almost impossible to stop the clamour.