In 2007, a tiny British theatre company called 1927 staged their first ever show at the Edinburgh Fringe – the darkly reimagined collection of fairytales and fables Between the Devil and the Deep Blue Sea. Now, almost a decade on, they are back where it all began – not at the Fringe but the Edinburgh International Festival, with their acclaimed Komische Oper production of The Magic Flute.

Two dramas of sex, sleaze and death in the postwar London underworld: to outsiders, this double bill of chamber operas by Charlotte Bray and Thomas Hyde might look like an unlikely opening night for the annual Presteigne Festival. That would be to overlook the artistic direction of George Vass, whose commitment to new music has made this short, spirited festival just a couple of valleys over from Hay-on-Wye a chamber-sized successor-in-spirit to Cheltenham.

There were two reasons why I didn’t return to the Albert Hall late on Friday night to hear Andras Schiff play Bach’s Goldberg Variations. The first was that one epic, Mahler’s Sixth in the stunning performance by Andris Nelsons and the Boston Symphony Orchestra, needed properly digesting. The other was that at Easter I’d heard Jeremy Denk play the Goldbergs in Weimar, and I wanted that approach to resonate, too – dynamic, continuous, revelatory, in a very different way from how I know Schiff approaches Bach.

Irish playwright Enda Walsh has been a regular presence at recent Edinburgh festivals – or, to be more precise, at the Fringe, with provocative works of rich linguistic lyricism including The Walworth Farce in 2007 and The New Electric Ballroom in 2008. This year marks his first foray into the Edinburgh International Festival, and it’s with a very different work. The Last Hotel, receiving its world premiere there, is Walsh’s first opera libretto, a collaboration with Irish composer Donnacha Dennehy.

At the beginning of Act Two of John Savournin’s production of HMS Pinafore, the quarterdeck is in darkness. Kevin Greenlaw’s Captain Corcoran steps out of his cabin, downs a brandy stiffener, and launches into his melancholy lament to the moon. Woodwinds echo the ends of sighing phrases as the strings pluck their accompaniment: something about this sounds familiar.

Ask opera-lovers to name their favourite one-acter and chances are the choice will be L’enfant et les sortilèges. Colette’s typically off-kilter fable of a destructive kid confronted with the objects and animals he’s damaged is set by Maurice Ravel to music of a depth which must have taken even that unshockable author by surprise. Ravel’s earlier L’heure espagnole, on the other hand, is much less likely to be top of the list.

English choirs and early music ensembles have a bad reputation for stiffness, formality – nothing wrong with the music, just the presentation. But with this dramatic and Italianate Orfeo, John Eliot Gardiner, his English Baroque Soloists and Monteverdi Choir, reminded us just what is possible when you combine English musicianship with a looser, more instinctive presentation.

This is the real Greek, bloody-fantastical thing. After the fascinating but flawed attempt to bring Aeschylus’s Oresteia into the 21st century, the Almeida has turned to a more tradition-conscious kind of experiment with Euripides’ last and greatest masterpiece.

Stop miking Bryn Terfel. Stop over-miking musicals; the show voices in a hybrid cast don’t need much. Too much ruined English National Opera’s recent Sweeney Todd, and in this Proms adaptation of Grange Park Opera’s summer crowd-pleaser it sent the voices ricocheting around the Albert Hall, making mush of the words and stridency of the few belt-it-out moments.

One hardly expects operas about historical figures to bother much with the actual facts of their lives. But Handel’s Xerxes must nevertheless rank as an extreme case. Instead of bridging the Hellespont and invading Greece with a million men – a campaign mentioned in passing as if it were some minor business trip – Xerxes spends his time philandering with his brother’s intended and generally creating emotional mayhem in the Persian court. Jenny Miller’s production transplants the action, somewhat irrelevantly, to a nightclub in, perhaps, Cairo or Palm Springs.