THE devil doesn't get the best tunes in The Rake's Progress, but he gets arguably the best role. In the new WNO production which has just opened in Cardiff, he also gets the best, most commanding voice: Bryn Terfel, back on old home territory. Terfel is in fact so commanding that he overwhelms the opera, sending its internal balance haywire. But then, the greatness of sound and presence in this mighty singer seems to have set the tone for Matthew Warchus's production, which scales up the opera's level of address across the board. The delicate quasi-period piece predicated by Stravinsky's neo-Mozartian music and W H Auden's neo- Augustan text has become the sort of roistering verismo epic that used to play the RSC in the 1980s. And as the show runs, it also outgrows the timescale its authors envisaged.

Strictly speaking, the libretto charts the decline of the Rake (in the manner of Hogarth's famous pictures) through little more than a year and a day. But Warchus enlarges the frame to encompass an Orlando-like progress through the centuries, from Hogarth's 1730s in the opening scene to 1951 (the year the Rake appeared) at the end (a front drop showing the concentric growth rings of a tree-trunk makes the point for anyone insensitive to costume). It's a clever idea: a natural extension of the game of displaced time that runs through the piece.

For The Rake's Progress is not merely a stage adaptation of Hogarth. Auden added the character of Nick Shadow, aka the devil, to spice up the story with a Faustian element. And like all operatic devils, this one is preoccupied with bartering souls in exchange for temporary freedoms from the precepts of the natural order. Especially the order of time. Just as Mephistopheles restores to Faust his lost youth, so Shadow, in the brothel scene, turns back the clocks. But it's a false freedom that leads only to the asylum, where - as the inmates sing - "Seasons, fashions never change". If there's a moral to the Rake - beyond the "devil makes work for idle hands" platitude of the epilogue - it must surely be that the only escape from the tyrannies of time and fortune comes courtesy of love. "In these fields of Elysium/ Space cannot alter nor time our love abate," sing Tom and Anne. "Here has no words for absence or estrangement/ Nor now a notion of almost or too late".

You'll appreciate, though, from these critical lines that Rake's Progress has a problem. It may well have the finest (English) libretto of any 20th- century opera, but the combination of Auden's convoluted prosody and Stravinsky's tendency to set it with deliberately misplaced emphases is not conducive to comprehension in performance. You really need to see the words in print to sort them out. But that said, one of the commendable things about WNO's production is the premium it places on audibility and diction. You don't often hear the jokes in the auction scene, for the overlay of bustle and business. But Warchus brings the action in a controlled manner to the front of the stage; and with a darker tenor than usual (Neil Jenkins) as the auctioneer, and slowish speeds from the conductor, Mark Wigglesworth, you catch every word. Which is some achievement.

Unfortunately, the general quality of the conducting isn't good: it doesn't get the brilliance, driven clarity or crispness that the score demands. But the voices are another matter. Terfel is stunning: every phrase, each move, intelligently thought through and immaculately done. This isn't just a big voice flexing muscle: it's extraordinary art, living and thinking on its feet. Paul Nilon sings the rake - a long role, almost constantly on stage - with fortitude and charm. And Alwyn Mellor transforms Anne Trulove (potentially a bore) into a glorious, heartfelt creature, soaring up to that alarmingly sus- tained high C at the end of her set aria with great style.

Overall, in fact, it's a great show: brave in the way it declares independence of the Hockney/ Cox Glyndebourne production, which has effectively defined the Rake's stage profile for 20 years; brave too in the way it makes a stand for the warmth and humanity that underpin a piece often dismissed as cold and formal. For this reason, if no other, this is an important production. It tours from mid-March and comes to Covent Garden on the 21st. Miss it and be damned.

The new English Touring Opera season opened at Sadler's Wells with two pieces notorious for the vocal demands they make of the dead. In Rigoletto, Gilda crawls from her sack, stabbed, and sings her heart out for the next 10 minutes. In Werther the eponymous hero, shot, does much the same. But ETO has two impressive young singers who could sing on all night so far as I'm concerned, and they add distinction to their respective shows.

The Rigoletto is a new production by Stephen Medcalf that creates real impact from a simple, abstract set (accommodating the requirements of the plot with no more contrivance than it deserves), a small but strong orchestra under Martin Andre, and an even smaller (eight-man) chorus. Tight, direct, intelligent, it's a terrific show, with world-class singing from the very lovely and technically outstanding Gilda of Gail Pearson: a star-in-waiting if ever I heard one.

The Werther plays like Strindberg, dark and spare, in a production by Robert Chevara which similarly achieves striking theatre from simple means. Sceptic that I am when it comes to Massenet, I can honestly say that I hadn't realised how viable a piece Werther is until I saw this production, which truly sorts out the substance from the packaging. And with fine voices like Geraint Dodd - covered but clean and expressive - and Roderick Williams, it makes a considerable impression. Forget Raymond Gubbay at the Albert Hall: this is opera for the people - touring throughout Britain, in English, at modest prices, and with a commitment to quality that doesn't presume first-time opera audiences to be witlessly undiscriminating.

The week's very best singing, though, came in Covent Garden's Semele: a tenderly ironic tragi-comedy - technically an oratorio but the nearest thing Handel wrote to opera in English - playing in a revival of John Copley's smotheringly decorous 1982 production. Felicity Palmer dazzles with her penetrating diction in the double role of Juno/Ino. But more dazzling still is Ruth Ann Swenson, the much-talked-about American soprano making a stunning UK debut in the opera's title role. Her coloratura is pin-sharp - the top notes pop like smartly burst balloons - but not mechanical: a perfect instance of technique enhanced by beauty, charm and personality. The Garden hasn't seen an act in quite this class for some time. It's singing to bind spells, drop jaws and raise the heart.

And, on a final heartening note, Paul Daniel changed his mind this week and agreed to become ENO's music director with effect from 1997. This is good news: Mafeking relieved. He is the right - perhaps the only - man to rescue ENO's flagging spirit. I shall lead the dancing in St Martins Lane myself.

'The Rakes Progress': Cardiff WNO (01222 878889), continues 7 Mar. ETO: Poole Arts Ctr (01202 685222), from Tues. 'Semele': ROH, WC2 (0171 304 4000), continues Mon & Fri.