This is an interesting review by Richard Bacon of Benjamin Shaw's Studies in Church Music. I feel it might be a benefit to us as we search out the issues surrounding choir.

Shaw begins his discussion of choirs with the admission that they "only gradually became a part of the worship."note18 He further acknowledges, "The development of the choir was also positively affected by the doctrine of the mass, for which many texts were set to Gregorian tunes." note19 This point should be setting off a few alarms. Choirs arose to provide the "sound track" for the idolatrous worship of the mass. Should we not regard choirs as suspect on that basis alone?
Shaw maintains that because there were choirs of ordained priests in the Old Testament, the use of choirs is justified in New Testament worship. When it is objected that priestly ceremonies associated with the temple form part of the weak and beggarly elements of the law, Shaw replies, "However, this assertion cannot stand up to examination, because it begs the question, 'in what way are choirs merely ceremonial?'" He proceeds to maintain that the existence of a heavenly choir in Revelation 5:9 is normative for our earthly worship. While Shaw speaks of others begging the question, it is he who begs the question, for he never demonstrates that Revelation 5:9 is normative, but instead assumes that which he is called upon to prove (the applicability of temple worship as portrayed in Revelation 5 to present day worship). note20
Shaw never explains in what way the assertion that the Old Testament priestly choirs were part of the ceremonial law begs the question. Perhaps he merely means to say that if one intends to assert that they were ceremonial that he should also explain in what way they were ceremonial or typical. That seems fair enough. But then after making that point, Shaw should have proceeded to examine the literature on the subject.
In his commentary on Psalm 149, Augustine maintained that the chorus or choir was typical and now consists of all Christians. In commenting on Psalm 150, he wrote, "The 'choir' praiseth God when society, made peaceful, praiseth him." The Old Testament choirs consisted entirely of Levites, as Rowland Ward demonstrates:
In the Old Testament public [temple] worship, instrumental music and singing was a priestly and Levitical function accompanying sacrifice. It was introduced by command of God (II Chronicles 29:25-30; Ezra 3:10-11), and was regarded as prophetic (I Chronicles 25:1-3, 5; II Chronicles 20:14; 29:25; 35:15, and note 'priests and prophets' in II Kings 23:2 is rendered 'priests and Levites' in the parallel passage, II Chronicles 34:30), and no cases in which the singing was unaccompanied can be established.
There are four features to note about Old Testament temple worship: (1) praise was not congregational but was by a priestly choir using inspired songs; (2) the singing was always accompanied by a priestly orchestra; (3) the singing and playing was always linked with sacrifice (I Chronicles 16:39- 42; II Chronicles 5; II Chronicles 29:25-30); (4) all these features were in accord with the command of God.
These four features have their fulfillment in the New Testament temple in which all the Lord's people form a holy priesthood. note21
With the advent of Christ and the establishment of the new and better covenant (Jeremiah 31:31-34; Ezekiel 36:25-27; Hebrews 8:13), we would anticipate certain changes in the form of worship. Christ prophesied during his earthly ministry that such would be the case (John 4:21). Further, the writer of Hebrews assured us that the ordinances of divine worship which appertained to the first covenant were only until the time of reformation (Hebrews 9:1-12). The Psalmist prophesied with the voice of Christ, "in the midst of the congregation [not just the priestly choir] will I praise thee" and "my praise shall be of thee in the great [large] congregation" (Psalm 22:22,25). As most know, this is the Psalm that was on the Savior's lips as he died upon the cross for the sins of the great congregation. But if there could be any doubt, the New Testament dispels it, for this passage is there interpreted, "in the midst of the church will I sing praise unto thee" (Hebrews 2:12b, emphasis added).
The priestly ministrations of the old covenant have been fulfilled in Christ (Hebrews 10:9; etc.). But choirs were part of the priestly ministrations of the old covenant (specifically a 288 voice choir and commanded by God through David in I Chronicles 25:1-7). However, the priestly functions of the new covenant belong to every believer (Romans 12:1; Philippians 2:17; 4:18; Hebrews 13:15-16).
Shaw claims to find a choir in Revelation 5:9. There is undoubtedly a chorus of voices singing praise to the Lamb in the passage (Revelation 5:7-10). Note, however, that the passage simultaneously proves less than Shaw requires when properly understood and more than he really desires if understood the way he has posited. Nothing in the passage indicates that those who were singing were doing so either "on behalf of the congregation" note22 or to the exclusion of others. In fact, verse 10 identifies them: "[thou] hast made us unto our God kings and priests: and we shall reign on the earth." Here in a passage that is filled with imagery of the temple (God's throne in verses 1 and 6; the Lamb in verse 6; beasts and elders in verses 6 and 8; incense burners in verse 8; priests in verse 10, etc.) we cannot expect to find literal, non-temple worship forms. We may as well look to Ezekiel for new covenant worship forms as to Revelation.
Additionally, if we take Revelation 5 as normative for worship and interpret it in a literal manner, then how do we answer those who maintain that we should add incense burning to our worship since it also is found in the worship of this passage? If the reply is that the vials of incense must be understood in a non-literal way as representing the prayers of God's church, then neither should the harps be understood in a literal way in the same passage. If incense is the church praying, there is no reason to understand the falling down and singing in any way other than the church worshipping and praising the Lamb of God. The passage does not teach (nor does any part of the New Testament teach) that some believers worship "on behalf of others."
The final passage Mr. Shaw adduces in favor of the use of choirs in new covenant worship is I Corinthians 14:26. Shaw reports, "In I Corinthians 14:26, Paul addresses the question of the proper use of spiritual gifts in the church: 'How is it then, brethren? when ye come together, every one of you hath a psalm...' Charles Hodge rightly said, 'Everyone is used distributively; one has this and another that.' (page 168)."
Paul was not exhorting the Corinthians in verse 26 as to what they ought to do, but was describing what they actually did. This fact is obvious from verses 27 and following in which Paul exhorted the church with a series of "let him" or "let them" statements. Further, if I Corinthians 14:26 were normative for present day worship (i.e. subsequent to the close the canon), it would require (or permit) the use of tongues and revelations as well as choirs.
Bishop John Lightfoot, the Erastian commissioner to the Westminster Assembly, understood the passage in light of his extensive research in both Hebrew idiom and the Jewish Talmud. In his New Testament Commentary, Horae Hebraicae et Talmudicae, Lightfoot said regarding the phrase, "what is it, brethren," "The apostle renders in Greek the phrase whm most common in the schools . . . . 'what is to be resolved in that case?'. . . . To the same sense the apostle in this place, ti oujn ejstin; what therefore is to be done in this case, about the use of an unknown tongue? He determines, 'I will pray with the Spirit, and I will pray with the understanding.'
"So verse 26: Ti ejstin, ajdelfoi; what is it, brethren? that is, 'what is to be done in this case, when everyone hath a psalm, hath a doctrine' &c. He determines, 'let all things be done to edification.'"
Lightfoot further maintained regarding I Corinthians 14:26, the meaning of "every one of you hath a psalm," etc. is, "when ye come together into one place, one is for having the time and worship spent chiefly in singing psalms, another in preaching, &c. One prefers singing of psalms, another a tongue, another preaching, etc." note23
The erudite Bishop Lightfoot demonstrated that the significance of the phrase "every one of you hath a psalm" is unrelated to choirs or solos or special music programs. Rather, Paul was pointing out yet another aspect of the life of the Corinthian church in which strife was prominent. Therefore the solution Paul commanded was that singing of Psalms, as well as everything else in worship, be done with understanding (I Corinthians 14:15) and for edification (I Corinthians 14:26).