Your essay Exclusive Psalmody - A Scriptural Evaluation grants us an foothold in the question: what is forbidden.

Let's think about this logically. If we accept that anything not prescribed in the Scriptures is prohibited, we must consider the writings of Calvin himself, indeed all of the church falters, as being outside the realm of holy study; that is to say, where do the Scriptures command the study of writings outside of the canon. This reasoning excludes the Westminister Confession, The works of Calvin, Luther, et al. Using this argument, the only document worthy of study is the Bible; any other study is therefore non spiritual.

Further, following this logic to its furthest conclusion, God provided the Scriptures in three primary languages, it was man who made the translations. Does this mean we must only study in the original tongue? That is the text directly intended by the Father, after all.

Obviously, these examples prove ridiculous. Of course, the church fathers have written excellent works worthy of study, not exclusive of the Bible but in addition; one would be hard pressed to find a church that believes in exclusive psalmody that does not reference a extra biblical text. And, it is dangerous to require believers to study the Word only in its original language, the reason the Reformation was so successful is the translation of the Bible into the vernacular; without this innovation, the individual man would have no access to the Scriptures.

It is irresponsible, and illogical, to use silence as prohibition; this is simply not how human beings work. God does not command us to drive cars, go caroling at Christmas, or blog; however, these things, and countless innovations not mentioned in the Bible, are good and useful for obedience and spiritual things.