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 clamour, but it is almost impossible to do so.
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 clamour, but it is almost impossible to do so.