As the festival season rolls towards August and Edinburgh, there is a momentary lull in July, which is often a good time for reflection; and this week I've been reflecting on the power of youth on the Scottish music scene, as exemplified in a few recent events.

At this point I should be talking about the National Youth Orchestra of Scotland. But NYOS has been run right down and we must await the results of work by the new chief executive, Joan Gibson, to see if there might be a phoenix-like rise from obscurity for the youth orchestra once regarded as a flagship.

There have, however, been a few startlingly impressive events recently that represent a mirror reflecting the quality of just some of the work that has taken place with young musicians based in Scotland. And I have to start in Perth, where, two weeks ago tonight, Perth Youth Orchestra appeared with the RSNO at the Gannochy Trust 75th anniversary concert in Perth Concert Hall.

It was an important night for the PYO: this is their own 50th anniversary. But of particular significance to the evening was the fact the young players would be side-by-side with the RSNO. Moreover, they were going to receive maximum exposure because on the programme that night they would feature in performances of major instrumental extracts from Bizet's Carmen. And that, in layman's terms, meant solo after solo after exposed solo.

The young players were coached and mentored by RSNO players. At the concert, with the burden of solos about to be carried by the youngsters, you could see RSNO principals peppered among them. I asked one RSNO principal how he saw his function. "I just have to sit there, ready to jump in if necessary," he said.

The children, despite the high-profile exposure and attendant nerves, were outstanding, not just musically, but with all the physical and psychological confidence you have to have, both in your playing colleagues and within yourself. It can be torture and terror out there on a stage with the spotlight on you. Try to imagine your lip tremulous, your breath control quavering, your fingers shaking. I was in a state of wonder, watching and listening to these expert youngsters, with not a tentative note in sight.

Then, just 10 days ago, I was smacked in the face by a performance of Schumann's great Piano Quintet in Cottiers Theatre by a group of students from the Royal Conservatoire of Scotland, a performance of a work often played splashily, with much Romantic flamboyance, here treated as a highly organised, well-structured and pellucid masterpiece, packed with Romantic sensitivity and expressiveness.

The group, the Csengele Quartet – a mixed-nation ensemble founded about three years ago by Romanian violinist Eva Demeter, with Lithuanian Ula Kinderyte on second violin, and two superb Glaswegians, David Munn and Christine Anderson, on cello and viola, joined a year or so ago by Canadian pianist Pearl Lynne-Chen – delivered a pristine and articulate account of the Schumann.

Last year they won a prize at the then RSAMD for chamber music playing in a competition adjudicated by Andy Saunders, French horn player and progenitor of the respected Cottier Chamber Project. He pronounced them winners and immediately offered them a gig in the Cottier Chamber Project, which was the concert last week to which I'm referring.

It was an extremely mature, thoughtfully organised and profoundly impressive account of one of the 19th-century's great Romantic masterpieces, and my instinct was that I couldn't wait to hear the group again. And at that point reality kicked in. This is a transitory experience: these powerhouse youngsters, presumably in their early twenties, progress, move on and fly the nest. Violist Anderson is heading south to college in London. Leader Demeter is off to Germany but hopes to retain her Glasgow links. Second violinist Kinderyte, I understand, might stay in Glasgow to study baroque violin. But the group will change. I believe they intend to try to continue, though they'll need a new violist.