Ed Sheeran may have conquered the global album charts again this week, but his latest record is unlikely to be remembered as his best. No.6 Collaborations Project is a collection of songs recorded alongside other artists and such multi-guest affairs often feel curiously unsatisfactory. They are more an enjoyable buffet than a nourishing feast.
The hugely popular British singer certainly surrounded himself with talent on No.6, including hip-hop stars such as Cardi B, Travis Scott, Eminem and Stormzy, but Sheeran's own raps on the record were not universally well received. Collaborative albums are a useful chance for musicians to change direction, but critical responses can vary wildly.
Often these diversifying stars are older singers. The great Welsh crooner Tom Jones, for example, was looking for a chart relaunch in 1999 so hooked up with newer names such as Robbie Williams and The Cardigans. The result, Reload, became his most successful album, going platinum in the UK. But it is now regarded as something of a novelty.
But you can take musical risks and remain classy. The renowned American singer Tony Bennett is perhaps the doyen of duets, and has worked with many modern female singers in his career, from the alt-country singer K D Lang (2002) to jazz star Diana Krall (2018). In between those, Bennett released one of modern music's most unexpected albums. Cheek to Cheek (2014) is his collection of classic jazz duets with Lady Gaga, who at the time was widely perceived as a provocative pop maverick.
That album – and the subsequent tour – was a bold departure for both artists, but certainly changed people's opinions of Gaga. Would her Oscar-winning work on the movie A Star is Born (2018) have been possible without the veteran singer's influence?
Bennett also recorded two multi-artist albums, Duets: An American Classic in 2006 and Duets II in 2011. A tasteful mix of classic standards and modern stars, the latter featured one particularly significant track – the final recording by Amy Winehouse, their cover of Body and Soul.
How collaborations actually occur can affect the quality of music produced hugely. Bennett's recordings benefited from proper studio sessions, but two seemingly similar albums by Frank Sinatra – Duets (1993) and Duets II (1994) – lack the same warmth. The impressive cast – Bono, Aretha Franklin, Willie Nelson – were all recorded remotely, then added digitally. And it shows.
Sinatra even used that process with his own son. Frank Junior was on tour when The Sinatra Family Wish You a Merry Christmas album was recorded in 1969, so his vocals were dubbed in later. The best Sinatra team-up record is arguably by Frank Senior's daughter, Nancy. Nancy and Lee (1968), featuring the brilliant singer/producer Lee Hazelwood, is a splendid collection of quirky, subversive pop.
Albums featuring only two artists are generally more coherent than multi-performer records. For example, Elton John's 1993 Duets featured a varied array of guests, including RuPaul and George Michael, singing covers, and the record feels insubstantial. But 2010's The Union is a sumptuous collection of new songs Elton concocted with the great American musician Leon Russell, a critical triumph that reignited interest in the latter's career. "He got his reputation back and felt fulfilled," John said after Russell died in 2016.
Alternative rockers The Flaming Lips also achieved an impressively varied line-up for 2012's The Flaming Lips and Heady Fwends. Everyone from Yoko Ono to Kesha featured, conjuring some of the band's more listenable material. Miley Cyrus appeared on the 2014 sequel, With a Little Help from my Fwends, which helped launch her edgier image.
Arguably the greatest guest-fuelled turnaround was that of Santana, a band whose records were failing to chart before they recorded with stars such as Lauryn Hill and CeeLo Green. The 1999 album Supernatural sold more than 30 million copies worldwide and collaborations became the band's whole ethos. Even tenor Placido Domingo appeared on Santana's 2002 follow-up, Shaman, before the eclectic appeal waned and the band returned to heavier roots.
Perhaps Sheeran will stick with hip-hop and collaborative records. Many great rap "solo" albums are awash with guests, after all. Take Dr Dre's 1992 debut, The Chronic, which helped launch Snoop Dogg's career as he features so often. Jay-Z left notable cameos uncredited on his classic 2001 opus The Blueprint, including Kanye West and Michael Jackson.
West was not as well known then, and in 2011 he shared equal billing with Jay-Z on one of the great rap crossover records, Watch the Throne. It began as a low-key EP but became a full-length epic, also featuring cameos from Beyonce, Frank Ocean, and even posthumous vocals from Curtis Mayfield and Otis Redding.
Sheeran will do well to ever challenge that throne.

