A far cry from the splendour of Westminster Abbey, the stage in the northwestern Bulgarian town of Montana was dilapidated and poorly lit.
But the audience was captivated.
"For me it was very important to perform in these towns, where there aren't many music events and where people are prepared to deprive themselves of something else in their lives to spend money on a ticket," 52-year-old Vassilev told AFP.
The audience at these "very special", sold-out performances is "brimming with expectations", he said, visibly moved.
Of all his listeners, they were "the most important", he said.
"It was wonderful. I'm shivering," businessman Micho Stavrov, 64, said of the electrifying performance.
Economics student Eva Yanakieva described the rare, top-notch concert as "breathtaking".
In this part of Bulgaria -- the European Union's poorest member state -- more than 40 percent of the population lives below the poverty line.
It is precisely this "contrast" between his native country and his adopted home in the UK that energises Vassilev.
Bulgaria, where he indulges in local specialities like banitsa and boza (a savoury pastry dish and a malt drink), "has never left his mind".
All genres of music'
Three decades ago, aged just 23, Vassilev became the youngest leader and first ever concertmaster at London's prestigious Royal Opera House (ROH).
Himself the son of musicians, the violinist is now the opera house's creative producer.
When he learned he had been appointed concertmaster at King Charles III's coronation, he was "particularly proud as a naturalised British citizen".
"By taking part in this sumptuous spectacle -- which only happens once or twice in 100 years -- we have become an integral part of history," he told AFP of the royal ceremony on May 6.
But Vassilev would not have missed the tour through rural Bulgaria for the world, despite the stress of starting straight after the regal pageant at Westminster.
Besides, the Bulgaria concerts were planned "long before the coronation", when Queen Elizabeth II was still alive, he added.
The coronation "was squeezed in before the town of Vratsa", where the tour began.
Vassilev dislikes to be pigeonholed as a classical musician, playing "whatever he likes", from Bach to flamenco, and Paganini to tango.
"It's important to be able to interpret all genres. Even Mozart played popular music," he said.
Direct from Bulgaria, Vassilev has already moved on to Tokyo to tour with London's Royal Ballet.
"We musicians are a nomadic tribe, always on the move."
