It seems like reviewers also use the term "reference" to refer to their own gear and the system into which any item under reviewed is being inserted.
For some reviewers, this reference system is designed to be as neutral and transparent as possible, to better aid in evaluating the equipment under review. Some reviewers also choose to have versatile equipment as their reference (for example, both XLR and RCA inputs and outputs). I have also read reviewers write about choosing well-known brands and gear for their reference system, so that experienced listeners might have an idea of the potential influence of the rest of the system.
On the other hand, some reviewers buy what they love, regardless of obscurity or potential coloration, limitations etc.
