So, what do we have?
On the Normative Principle side, the argument for the use of instrumental accompaniment to singing in worship wins, hands down, although it is easily conceded that both forms of singing are fully acceptable forms of worship.
On the Regulative Principle side, there is significant scripture supporting the use of instrumental accompaniment to singing (e.g. the Psalms and Revelation). In order to make the Regulative Principle accomplish the prohibition of instrumental accompaniment, these scriptures must be dismissed. This has been accomplished by the following explanations:
1. Dispensationalists will claim that the Psalms are OT and, therefore, irrelevant to NT worship (despite several references in the NT to singing Psalms).
2. Dispensationalists maintain that the worship in Revelation is yet future and has no bearing whatsoever on the worship of the Church.
3. It is argued that the Psalms which mention various musical instruments were never used in the liturgical worship of the Jewish people.
4. It is argued that the worship in heaven is distinct and different from the worship in the Church.
5. One of the more peculiar arguments I have personally encountered is based on Revelation 8:1 in which it is posited that the silence in heaven then was directly related to the exact time of the death of Jesus Christ. The argument goes that all of heaven ceased its worship when Christ died and, therefore, when the Church meets to remember the death of Christ in the Eucharist, it is profoundly out of character to use instrumental accompaniment to singing. The obvious flaw to this argument is that if the church is to follow that model, then there must be complete and utter silence - no singing, no speaking, nothing.
It appears to me that as Rev Randy has astutely observed, whatever form our singing takes, it must be true worship with Jesus Christ as its very heart.