The GIRM is pretty clear on this. "Unity of their voices." Congregational singing is preferred.

Doesn't mean one can't do choral-only music. Just means it isn't preferred.

If you think you know better than the authors of the GIRM, just say so. (Personally, I prefer to ignore the GIRM on this point) But let's not pretend the GIRM endorses a model of music at Communion which excludes the congregation.

Gavin - I don't have to pretend...
GIRM 87 explicitly states that the choir may sing the chant alone. The real question is whether the authors of the GIRM knew better than themselves. Why juxtapose a seeming contradiction like this? I see it as describing legitimate variety in musical practice, rather than excluding the choir and then "accidentally" allowing it to sing alone in the very next paragraph.

The GIRM is pretty clear on this. "Unity of their voices." Congregational singing is preferred.

It is crystal clear in point of fact. Unfortuntely and despite anecdotal accounts positive or negative, that particular catechesis remains stuck between being a lacunae or shibboleth, particularly in the minds of many celebrants. These same fellows trumpet the principle fail to ever address that very point from the ambo, or otherwise insist or cajole their flock to "get" into the preferred habit. They're often the same clerics who suppress the singing of the Pater Noster out of concern for the one person out there who "can't" sing it.
Try to avoid responding to my observation as unreasonable, I've experienced far too many autocrats who insist upon the former point with little success, and impose the latter despite the whole-throated singing of the Our Father when it does occur.

With different "emphasis added" to point out that the GIRM does not speak in these items about a hymn being sung during communion; on the contrary, it only addresses a hymn being sung after Communion. Nowhere does it equate Communion chant with hymn after Communion:

86. While the priest is receiving the Sacrament, the Communion chant is begun. Its purpose is to express the communicants’ union in spirit by means of the unity of their voices, to show joy of heart, and to highlight more clearly the “communitarian” nature of the procession to receive Communion. The singing is continued for as long as the Sacrament is being administered to the faithful. If, however, there is to be a hymn after Communion, the Communion chant should be ended in a timely manner.

It seems that ending the Communion chant in a timely matter simply means not to drag it out beyond the administration of Communion, but it does not mean that one ends the chant early so as to start a congregational hymn while Communion is still being administered.

87. In the dioceses of the United States of America there are four options for the Communion chant:

(1) the antiphon from The Roman Missal or the Psalm from the Roman Gradual as set to music there or in another musical setting;
(2) the seasonal antiphon and Psalm of the Simple Gradual;
(3) a song from another collection of psalms and antiphons, approved by the United States Conference of Catholic Bishops or the diocesan Bishop, including psalms arranged in responsorial or metrical forms;
(4) a suitable liturgical song chosen in accordance with no. 86.

This is sung either by the choir alone or by the choir or cantor with the people.

88. When the distribution of Communion is finished, as circumstances suggest, the priest and faithful spend some time praying privately. If desired, a psalm or other canticle of praise or a hymn may also be sung by the entire congregation.

Item 88 only refers to what happens when distribution of Communion is finished.

Just read what's there and don't bend it to your own wishes.

You are exactly right Charles...
We do the communion chant until the communion procession is over, then during the cleaning of the vessels we sing a hymn of thanksgiving or praise. Then silence.

The only alteration to this is when the Communion Chant and its verses is finished before the procession is complete. Then we start the hymn early and sing the Marian Antiphon of the Season as a meditative piece while the vessels are cleansed.

Regardless, we always provide sacred silence for at least a couple of minutes.

Saint Edward, Newark, CA Solemnity of Saints Peter & Paul: 10:00 AM Missa Cantata
Full Gregorian Proper; Palestrina "Missa: Tu es Petrus" (Kyrie, Gloria, Agnus Dei III) with Mass IV Sanctus & Agnus Dei I & II; Offertory Motet: "Constitues eos" a 5 ... Palestrina; Communion Motet: "Tu es Petrus" .... Palestrina. Closing Hymn to the Blessed Virgin: "Salve Regina" ... Solemn Tone

We have the Mass of Thanksgiving for our Cathedral's newly ordained priest who plans to chant the entire Mass (including the Roman Canon).

I don't know whether this is a real omission, but I would have liked to see the Our Father among the sung parts of Mass on Matthew's fine program.

Is the concept of "chant the entire Mass" foreign to folks?

Of course the Our Father will be sung.

In fact, I can't recall a Sunday Mass at any church, since moving to Phoenix, that has not had the Our Father sung.

Let's get back to the main topic, shall we?