Analyzing DACs

As I am new to the hifi hobby, reading various product reviews and noting the details of the test environment have made me very confused.  I understand Stereophile is the hifi bible. In the publication’s DAC published tests the reviewers almost always tested the DAC connected directly to the amplifier. I think I understand why—nothing in the chain influencing the DAC sound. Is that the correct assumption? If that’s the case why incorporate a preamp if the DAC has a preamp section that is a common feature even on high end DACs? I’m in the market for a new DAC. I’m trying to avoid unnecessary components if possible. Any thoughts would be appreciated. Thanks.