Sometimes you hear something new and your perspective on music shifts seismically, making everything you were listening to previously sound safe and predictable by comparison. Inevitably, as one gets older and more musically knowledgeable, such moments are fewer and further between; either the shock of the new isn’t as high-voltage as it used to be, or it just irritates rather than stimulates. And so it was a pleasant surprise when, one morning – heralded by a storm of tape hiss and an enthusiastically bashed tribal drum – a new band called tUnE-yArDs (aka Merrill Garbus) came at me from the hi-fi speakers like a Dadaist, feminist pop warrior.

How much did I like this show? Well, here’s a clue: at the end, the only really bad thing I could think of was that the bass guitar could have been a bit louder. I’ve seen David Gray on stage quite a few times now, and this was easily the most satisfying show, the one that did justice to his voice, his music, his songs, and especially his lyrics, which were, almost uniquely for such an event, audible and understandable almost word for word.

A question passed through my mind before last night’s Donovan show. Special guests were billed for this celebration of his classic psychedelic album Sunshine Superman. Perhaps they'd include Jeff Beck or Jimmy Page, both of whom played on Donovan's records in the Sixties. Then, introducing “Sunshine Superman”, Donovan mentions the then-session player Jimmy Page, who walks on and joins in. Seeing Page reunited with his pre-Led Zeppelin, pre-Yardbirds session man self was incredible. Needless to say, he played great. Donovan shone.

Did Wolfmother spring from outer space, or drift down to Earth from the tail of a comet? Did they slip into our age from another dimension, burrowing through a wormhole in the space-time continuum to land in Sydney, Australia in the 21st century? Where did they come from? Never, except for tribute bands, have I witnessed a group performing in one era whose music owes so much to another. These hairy Australian rockers are steeped in the lore of late-Sixties psychedelia and early-Seventies hard rock, their singer Andrew Stockdale shrieks like Ozzy Osbourne, Ian Gillan and the rest of the rock-wailers, and their songs are masterpieces of riffery, with all manner of proggy noodling and tricky time signatures and changes of pace.

After all, the band’s success rides on their mellifluous Sixties sound.

Sometimes you stare at live bands and question why they bother. It’s a pact - the band plays, the audience looks on and claps. Last night’s debut British show by Chicago's Disappears raised that question. The night before, they’d played Amsterdam’s Paradiso and here they were at a venue in central London with an audience of 60 or 70. White-light intense, their conviction shone. This hypnotic show became a secret, even with the draw of Sonic Youth's drummer Steve Shelley in their line-up. But still, Disappears delivered.

At one level the day of the single is gone - the 7-inch, the CD, the physical format - and yet, at another it's more relevant than ever. Sure, any track can now be downloaded from an album and hit the charts but singles, downloads - chosen representative songs - still give the best snapshot of what an artist is capable of. With this in mind, theartsdesk gleefully tucked into the latest batch of releases which includes Depeche Mode, Arctic Monkeys, pop, rave, folk and a whole lot more besides.

The world of artist and entomologist Tessa Farmer really is a world, wholly self-contained and free of human kind – unless you see her tiny warring fairies as symbolic of mankind’s conscience-free decimation of our planet’s environment and co-inhabitants. And it’s hard not to when you see them relentlessly picking over the corpse of a bird, mugging a mouse, or scrapping with a hornet, their tiny skeletal forms so industriously yet somehow amusingly destructive.

A guitar with one string? There is indeed such a thing. It’s played by Seasick Steve, and it consists of a stubby plank of wood, a pick-up and a couple of nails. And a string. The man born 70 years ago as Steven Wold plays it with a slide, and it makes a fabulous, sleazy sound. It’s one of a collection of manky-looking instruments played by Seasick Steve, the former hobo, drifter, session musician and studio engineer who has experienced a late blossoming in popularity as a bluesman and raconteur.

Explosions, 40ft flames, light shows and back projections. It may have been at the Dome but at times it felt more like being in a music video. A mini-film opened the concert. Rush circa 1973 were boys called Rash, and they’d play only when professor Alex Lifeson operated his music machine. The contraption also had a button marked “Time Machine”. When pressed this catapulted the band, on stage, back and forth through their 37-year career. Every time the trio played songs from a different era, screens announced the year.