Unlike other instrumental works by the composer, most notably the symphonies and the piano concertos, Mozart's violin sonatas – or, more correctly, his sonatas for fortepiano and violin – have not appeared on the scene of historically informed performance practice until relatively recently. One recording of all the sonatas (by Sigiswald Kuijken and Luc Devos, Accent ACC20041; five discs) was completed in 2005, and another one just this summer (by Rachel Podger and Gary Cooper, Channel Classics CCS SA 21804, 22805, 23606, 24607, 25608, 26208 and 28109, 2004–2009; eight discs). Andrew Manze and Richard Egarr have contributed selections, as have Jaap Schröder and Lambert Orkis. Nevertheless, there is still plenty of room on the market for yet further forays into the subtle realm of Mozart's duo sonatas – particularly since the balance of violin and piano in these truly dialogic works is far more convincingly achieved on period instruments than it is on their modern counterparts.

The two artists under scrutiny here are presenting their first collaboration on disc, having appeared as duo partners in concerts for some years now. Both the violinist Petra Müllejans (perhaps better known to a wider concert-going and CD-buying public as one of the two leaders and artistic directors of the Freiburger Barockorchester) and the pianist Kristian Bezuidenhout are primarily period-instrument performers – but both emphasize on their respective websites (<http://www.barockorchester.de/englisch/e_opetra.htm> and <http://kristianbezuidenhout.com/>) that they are also keen performers of modern repertories on modern instruments (Müllejans indeed as a player of Klezmer, tango and czardas). The claim in Müllejans's biography that her performances on the baroque violin are ‘quite unusual as she combines authentic period style with emotional spontaneity’ might rub many the wrong way, as it implies that those exclusively engaged in historically informed performance lack such emotional spontaneity, but she may be forgiven for it by presenting a selection of Mozart sonatas on disc in a manner that offers ample support to her somewhat ambitious claim. Here, indeed, is ‘period’ performance as we have come to expect it from the best practitioners in the field: flawless technique combined with breadth of conception, full of energy and life. It may lack the raw and uncompromising (sometimes edgy) power of the Podger/Cooper collaboration on the one hand, and the refinement and poised confidence of Manze/Egarr on the other; but in terms of ensemble coherence and overall artistic merit, Müllejans and Bezuidenhout easily hold their own against their competitors, and may perhaps even surpass them in the eyes of some.

The duo have chosen some of the ‘showpieces’ of the repertory: the ‘Strinasacchi’ Sonata in B flat major, k454, named after the famed Italian violinist for whom it was written, as the most technically demanding; the ‘One-hour’ Sonata in G major, k379 (nicknamed because the composer claimed he had written it within one hour in 1781); the extroverted Sonata in C major k296 from Mannheim; and the rarely heard but nevertheless delightful set of variations on the French song ‘Au bord d'une fontaine’ (‘Hélas, j'ai perdu mon amant’), k360. (The entire programme is competently introduced by Bezuidenhout himself in an attractive and well-presented booklet.) All four works are, in the nomenclature of the time, composed for ‘pianoforte and violin’ (not vice versa – a practice which persisted well into the nineteenth century), but they are in essence dialogues, conversations of equal partners; and the way in which Müllejans and Bezuidenhout ‘converse’ with one another is harmonious and intimate indeed. This could (or should) be taken for granted, but their musical interaction remains impressive, especially since there is a great and gratifying sense of rhythmic freedom, gentle variations of tempo from one variation to another, subtle rubatos and little pauses at the ends of phrases to take a figurative breath. This overall sense of pace and breadth is in fact the most outstanding feature of the recording, brought out to greatest effect in the slow movements and the sets of variations (the dreamy Adagio variation in the second movement of k379, for example, is utterly enchanting). The playing style contains all the good things we have become accustomed to from historically informed performers without being pretentiously learned, with judicious vibrato and the occasional portamento in the violin, unobtrusive embellishments in both instruments, and mini-cadenzas in the fortepiano bridging the occasional fermata.

The quibbles are minor. For unexplained reasons (perhaps lack of disc space), the developments and recapitulations of the sonata-form movements are not repeated. Dynamic contrasts are perhaps not explored as much as they could have been, with good portions of the music resting in a comfortable (while admittedly very beautiful) range of mezzo piano to mezzo forte, and even with some odd choices in k454, where the dynamics written by the composer seem reversed in the recording. This is a pity, all the more so since the abovementioned Adagio and some other passages show the duo to have an utterly ravishing pianissimo at their disposal, also some crisply accentuated forte accents when needed. All in all, however, this is an utterly engaging recording of utterly engaging music; it is to be hoped that both the the duo and Harmonia Mundi meet with enough success – both commercial and artistic – to continue with their efforts.