Classical Opera Company, Wigmore Hall, London <br></br>Park Lane Group Young Artists, Purcell Room London

What makes a Significant Cultural Event? The cynic might point to money, meaning anything from expensive soloists to a lavish set. The pragmatist to historical importance, meaning high-profile commissions, debuts, or farewells. The idealist to rarity, meaning famously difficult works. Does quality come into the equation? Not always. Sophie's Choice was the ultimate SCE of 2002 and none the better for that status. But should an opera company invest X hundred thousand pounds on whirligigs and special effects or an orchestra devote their entire guest artists budget to one soprano's dressing room hamper, you can bet your bottom dollar that the critics will be there.

So where does this leave those ensembles who boast no big name soloists and are simply performing minor works of one of the world's greatest composers in as unaffected, accurate and affectionate a fashion as they can? In the case of the Classical Opera Company – whose performance of Arne's rarely-heard Artaxerxes clashed head-on with the premiere of Sophie's Choice – it leaves them with one of the most loudly enthusiastic audiences to be heard at that hush-voiced temple of quality over hype, the Wigmore Hall.

The Classical Opera Company's formula is simple: through smart programming, a brisk, unpretentious performance style, judiciously concentrated repertoire, and conductor Ian Page's remarkable talent for spotting the most attractive young singers while they're still affordable, they manage to entertain and inform. Little details count. Characterful spoken commentaries focus attention on the stage (Page's scholarly programme notes can be read later), while the orchestra's quick-off-the-mark attack conveys the kind of joy in performance that often seems in inverse proportion to an ensemble's profile. Indeed, give or take a few glitches in the imitative string passages – one little detail COC need to address – and some hasty final chords, Mozart in Italy was a wholly joyous affair.

If COC's final chords were somewhat indeterminate in length (a problem endemic to period instrument performances), the notes leading up to them were delicious. Page's expressivity and confidence have grown exponentially since his last musicological travelogue, Mozart in London, making the structure and sound-world of Mozart's juvenilia – and that of Hasse and Jommelli – newly vital. He has a good ear for effect; teasing out contrasts from the simplest material and wringing pathos from passing dissonances. And though I wouldn't queue round the block to hear either of the two D major symphonies (K81 and K84), the Symphony in G major K74, with its bubbling pizzicato, was captivating.

So too were sopranos Sarah Fox and Cora Burggraaf. If Fox has the artistic edge, the warmth of presence, and the wisdom to understand where to colour and where to cool her tone – "Pallide ombre" from Mitridate was quite beautifully shaped – Burggraaf is one of the most stunning high sopranos to emerge in the last decade. It's a remarkable voice; a little artless as yet but with such a ravishing natural vibrato – like a stratospheric Bartoli minus the mannerisms – that unless she can't act her way out of a paper bag, hers will be a very exciting career. Should I bewail the fact that this group has yet to attract the attention it deserves? My feeling is that that will come. And the next time there's a clash between COC and an SCE, I know where I'll be.

The Park Lane Group Young Artists series is a mixed blessing; casting out gems in terms of its virtuosic alumni but making the listener suffer programming that can be, to put it very politely, uncompromising. With a total of 10 programmes of music from the last 50 years, the trick is in finding the right one; though without an encyclopaedic knowledge of new music, this is a hard call, as I discovered. With the greatest respect to bass-clarinettist Sarah Watts – whose technical command and sheer chutzpah can be in no doubt after performing three consecutive unaccompanied works, each of 20-minutes duration – I take issue with her statement that "there is only one sound better than one bass clarinet: multiple bass clarinets."

Moreover, I'd rather eat my own cat while listening to Mahler Eight than have to listen again to Michael Smetanin's Ladder of Escape for bass clarinet and taped bass clarinets. "Simply happy disco music!!!" (as Sarah Watts wrote) it ain't. It may be that I just happened to go to the only unbalanced programme in the series – violin and piano duo Harriet Mackenzie and Christopher Glynn barely got a look in in this concert – but isn't it time either to widen the PLG remit to include music from other periods or to ensure that only the good stuff gets through? Because there is some. Lots, in fact. But maybe not for solo bass clarinet.

a.picard@independent.co.uk