Some useful lessons can be learned from Boston Academy of Music’s delightful new production of The Mikado, which it presented at the Emerson Majestic last weekend. One is that it’s always possible to improve. Another is that expectations, however much they’re based on experience, should never be trusted. And another is that anything can work if it’s done right.

BAM has offered a lot of disappointing Gilbert & Sullivan. Its Mikado five years ago was leaden — like a bad comedian killing every joke. H.M.S. Pinafore, as staged at the USS Constitution, was more arch than witty — mechanical, gimmicky, dehumanized. When would someone do a G&S operetta that focused on the real feelings of the characters, however preposterous their predicaments?

But the problem may have been that these productions weren’t absurd or campy enough. Because what stage director Ira Siff (artistic director of New York’s La Gran Scena Opera Co.) came up with for this Mikado was not only outrageously silly, even verging on the tasteless, but also brilliantly and compulsively inventive. Hardly a moment went by without some inspired, fresh response to Gilbert’s absurdist language or Sullivan’s lovely and witty score. Gilbert’s plot, about Ko-Ko, the "cheap tailor" whom the Emperor of Japan (the Mikado) has elevated to the post of Lord High Executioner of the town of Titipu, is essentially a satire on the propriety and egotism of the British. For Siff, no one is safe and nothing is sacred.

Including chronology. Every G&S operetta "updates" some of Gilbert’s more dated references. The Mikado’s catalogue of criminal activities includes "Bach, interwoven/With Spohr and Beethoven,/At classical Monday Pops"; here it was "Schlock interwoven/With rock and Beethoven —/Typical Boston Pops." Ko-Ko’s "little list" of society offenders embraced "that singular anomaly, the Boston motorist" (rather than "the lady novelist" — no longer anomalous). The one line I wish hadn’t been cut was about the perfect torture the Mikado has devised for the pool shark: "a cloth untrue, with a twisted cue, and elliptical billiard balls" (guess what was substituted!).

These anachronisms worked because Siff made them part of the very texture. Helen H. Friedman’s costumes were lavishly 19th-century, but the Gentlemen of Japan ate from take-out cartons, took photos from disposable cameras, and carried portable CD players in their obis. Nanki-Poo, the Mikado’s son disguised as a "wand’ring minstrel" (a second trombone!), offered them his "ballads, songs, and snatches" on disc ("Nanki-Poo’s Greatest Hits" was his ad slogan).

Even more revealing was the way nearly every phrase evoked a specific gestural response. When the Gentlemen of Japan introduce their "attitudes queer and quaint," their "attitude" was incessant bowing, and their musically extended "Ohhhh" expressed their aching sacroiliacs (as opposed to expressing nothing). The Wand’ring Minstrel checked out the worn soles of his shoes (from all that "wand’ring"). The apex of sublimity came when the homely Katisha, the Mikado’s "daughter-in-law-elect," from whose clutches Nanki-Poo has escaped, accused her fleeing lover of being "rash" and "base." "Oh rash!" she sang, and scratched his chest; "Oh base!" she growled, and pointed to the double-bass players in the orchestra pit.

As the haughty but bribable Pooh-Bah, marvelous Keith Jurosko (a Gran Scena alum and Cyril Ritchard look-alike) made you believe he was "born sneering." Since he’s every public official rolled into one (including the Archbishop of Canterbury "and the ex-director of Massport"), Siff also made him a living inventory of ethnic stereotypes (parsimonious Scotsman finance minister, Jewish lawyer, Irish constable). He was Groucho, rattling off the list of his positions, and Mae West as Ko-Ko’s "private secretary." Aaron Engebreth, promoted to a featured roll from the chorus of recent BAM shows, was more "Swish-Tush" than Pish-Tush — and a boozer to boot. But if you’re going to mock fat ugly women and Jewish shysters, why not gay drunks as well? At the end, African-American bass Philip Lima (infinitely livelier as the Mikado than he was five years ago), took the pale hand of Nanki-Poo (tenor Daniel Lockwood), compared their skin colors, and exclaimed: "My son?" Any of this could have been offensive if it hadn’t been carried out with such knowingly affectionate un-PC high spirits.

Siff’s staging was also very musical. What he did with snapping fans and a row of opening and closing parasols is worthy of Busby Berkeley. And worthy of conductor Julian Wachner, who kept things moving along not by rushing but by varying the pace and allowing Sullivan’s enchanting tunes to take wing. The excellent singers were at once sincere and self-mocking. Joanna Mongiardo was an endearingly self-absorbed Yum-Yum ("Yes, I am indeed beautiful! . . . Can this be vanity? No! . . . I am a child of nature, and take after my mother"); Lockwood an artless but lilting Nanki-Poo. Engebreth, Lima, Laurie Lemley (Pitti-Sing), Wendy Bryn-Harmer (a horn-rimmed Peep-Bo), and full-voiced Sharon Brown (the candy-loving Katisha, who steps out of a huge wedding cake) all seemed to be paying attention to one another — and, like me, enjoying what they saw.

This season, BAM artistic director Richard Conrad has been celebrating the 40th anniversary of his opera debut. As Ko-Ko, winking, he added to his little list: "former opera singers who resort to G&S." His own G&S is broad, and his voice (singing or speaking) no longer possesses the necessary G&S crispness. But he can be both touching and funny. Like Mrs. Slocum in Are You Being Served? (even with a tape measure around his neck), he frequently interjected: "And I am unanimous in this!" For "Tit-Willow," he was in better singing voice than he was in last month’s Donizetti opera, L’elisir d’amore, though he was upstaged (literally) by Brown’s Katisha devouring chocolates from the heart-shaped candy box that this canny Ko-Ko knew was the best way to her heart.

WHILE SEIJI OZAWA IS AWAY, the BSO has had a string of moderately satisfying concerts led by other conductors. Assistant conductor Federico Cortese put together a lively program that included two BSO firsts. Charles Ives’s Ragtime Dances, were sketched between 1900 and 1904 but not played anywhere for 70 years. We got three of the four dances, by turns acerbic and soupy and full of characteristic Ivesian interpenetrations of piano rags and hymn tunes. Cortese also gave BSO audiences their first taste of 75-year-old Rumanian-born Hungarian composer György Kurtág. Grabstein für Stephan, completed in 1989, is a mysteriously hushed dirge — spare, fragmented, and played in a darkened hall — with instruments of mourning (muted trumpets, chimes, gong, drums taps, brushed cymbals) surrounding a central guitarist protagonist, plus two small groups of brasses and some shockingly shrill whistles and alarms positioned in the balcony.

Brazilian pianist Nelson Freire’s tendinitis was the cause of yet another cancellation in a season riddled with them. Joseph Kalichstein replaced him, at short notice, with a different Mozart piano concerto from the originally scheduled No. 9 (in E-flat, K.271); instead we got No. 27 (in B-flat, K.595), his last — music heartbreaking in its profound simplicity and heavenly joy. Kalichstein’s brittle, muffled tone didn’t seem to connect. In Schubert’s endearing Fourth Symphony (the Tragic), however, Cortese provided both nervous tension and songful legato — and a scintillating Finale that looked forward to rollicking Mendelssohn.

The following week, my favorite Russian, Gennady Rozhdestvensky, was back on the podium with more unfamiliar repertoire, starting with the overture to Wagner’s second completed opera, Das Liebesverbot ("The Ban on Love" — based on Shakespeare’s Measure for Measure), in a performance tingling with tambourine and triangle and clickety-click giddyap castanets, with bass-trombonist Douglas Yeo once again playing his historic 1855 ophicleide. This novelty was followed by the BSO debut of Arnold Schoenberg’s charmingly dour 1934 Suite in G (yes, it’s tonal!) for String Orchestra, with its bent echoes of Tchaikovsky’s Serenade for Strings and another suite of dances closer to home, Stravinsky’s 1928 neo-classical ballet (also for strings) Apollon Musagète, which George Balanchine choreographed and is now known as Apollo.

The rest of the concert was Shostakovich’s 13th Symphony, Babi Yar. In 1962, this was a politically courageous work — a blistering attack on anti-Semitism, setting Yevgeny Yevtushenko’s melodramatic poems about the Nazi shooting in Ukraine (with local acquiescence) of some 100,000 Jews. Russian bass Sergei Aleksashkin intoned the cycle with power but without much variety and oddly little resonance. The men of the Tanglewood Festival Chorus sang, in Russian, with gleaming ferocity and tenderness. It was good to have a Russian take on this music — but it’s far from the composer’s most inspired work.

Someone at the BSO must be pushing tonal Schoenberg. The next conductor up to bat, Roberto Abbado (Claudio Abbado’s nephew), gave us the father-of-atonality’s impassioned pre-atonal tone poem, Pelleas und Melisande (begun in 1902, the year of the world premiere of Debussy’s great opera, which was also suggested by Maetterlinck’s play). I’ve been impressed more — though not greatly — with Abbado’s finesse than with his insight, and though it was good to hear the piece played by the BSO, it didn’t approach the seductive heat Pierre Boulez and the London Philharmonic provided at Carnegie Hall two years ago.

The program opened with 21-year-old Italian pianist Gianluca Cascioli playing Beethoven’s Piano Concerto No. 1 (actually his third piano concerto). Cascioli has a rippling fleetness (those glittering trills!) without producing great depth of tone. Even with a diminished orchestra, he was sometimes hard to hear. Maybe he was more convincing on the radio. Still, there were memorable effects, like the almost Debussyan arpeggios cascading over the quietly staccato orchestra in the first movement and ending in a big-finish falling glissando. He played a five-minute cadenza Beethoven wrote years later (a mini-Appassionata). It unbalances the proportions and decentralizes the 18th-century style of this still-youthful work. But without the orchestra, it was the playing you could hear best.

This weekend, Robert Spano leads the BSO in the program that’s become famous for what has been dropped from it: three choruses from John Adams’s opera about terrorism, The Death of Klinghoffer — from which the management wanted to protect us. Maybe if the BSO had a stronger history of playing music that deals with challenging contemporary issues, this cancellation might have been less disappointing. And less controversial.