The difference between a string quartet and a string orchestra is not only one of scale. The most obvious fundamental difference is that the string orchestra is a quintet: even the most straightforward orchestrated quartet will have an additional base-line, generally an octave below the original, with a consequent risk of ponderous bottom-heaviness. A more radical difference is that ten violins do not sound like one violin multiplied by ten. Not only is the character of the sound quite dissimilar, but passages that are awkwardly high or fast have, in the hands of a solo player, a feeling of personal endeavour or of hazards triumphantly or with difficulty overcome that can be used (by the composer and the performer) to great expressive ends; when ten or a dozen players are trying to negotiate such difficulties simultaneously and in precise unison there is always a danger that the result will sound mechanical or meretricious (like musical synchronized swimming), quite aside from the tendency of massed violins to sound glassy in very high positions.
Mahler obviously knew all this, and even he could not always avoid robbing the music of its essential nature in these and other ways (a tutti for four instruments, as at the beginning of the Scherzo, for instance, is of quite different weight and texture from one for 40), but it seems that he was concerned to protect elements of Schubert's imagination that he felt to be under-characterized (for the post-romantic listener, at any rate) by the chamber scoring. A striking example of what he must have been thinking of occurs in the finale, where the incessant long-short rhythm falters and fades, leaving the first violin uneasily reiterating it with virtually no accompaniment: a full violin section somehow gives this passage an extraordinary feeling of aloneness that it would be difficult for a solo violin (who is, in a sense, always heard alone) to convey. Other moments are intensified by discreet changes of scoring: the repeats in the theme of the variation movement, for example, are given an eerie remoteness by being played with mutes. Sometimes an effect is heightened by the very fact that it is a string orchestra, not a quartet, that we are hearing: the fearsome impetus of the finale's prestissimo coda, the ashen pallor at the conclusion of the variations. Elsewhere, though the emotion is often unavoidably generalized (the wounded fluttering of the first-violin line in the slow movement's first variation sounds oddly mechanical, deprived of personality, expressively though it is played), it is the subtle restraint of Mahler's arrangement that one most admires: the moments when he knows that the basses must be silent for fear of obscuring an important cello phrase, or when the bass reinforcement need only be a discreet pizzicato.
An intelligent following-through of Mahler's perceptions is the hallmark of Jeffrey Tate's reading: in phrasing and pacing this is not an enlarged chamber performance but one that seeks out aspects and resonances that a string orchestra can point up; the huge ritardando at the end of the first movement or the extremely controlled crescendo to the second subject of the finale (not the first) are effects that would scarcely work on a quartet but are impressive and illuminating here. His orchestra minimizes the appalling difficulties of playing such music with the necessary precision and crispness; the basses in particular perform amazing feats, and the recording is as clean as one could wish. Call it an essay on certain features of Schubert's quartet rather than a performance of it if you like, but it is an essay filled with insight; fittingly and satisfyingly it is prefaced by a movingly intense account of the song from which Schubert's masterpiece sprang. '