Pointing out the composer's characteristic "turn-on-a-dime" changes of mood and colour, Fejer and his colleagues are amazed Haydn could be so inventive, working in rural isolation, far from the sophistication of Vienna.
He himself has been to Eisenstadt, where Haydn was posted, visiting its castle and the pubs in the nearby town that doubtlessly counted the composer amongst their patrons.
"Just imagine the music he must have heard there, dashed off with such a wonderful mix of Hungarian, Austrian and gypsy styles," Fejer says.
"And that tipsy gypsy music must have been an El Dorado when it came to inspiring all those Haydn minuets."
At the other end of tomorrow night's concert, Dvorak's final quartet reveals the Czech composer's joy in returning home after spending three years in New York, where he wrote his well-known New World Symphony and American Quartet.
Here, the four musicians will lightening their approach so that the music becomes, says Fejer, frothier and with the right sparkle.
The cellist talks more than once of Dvorak wearing his romantic heart on his sleeve, and he finds much the same spirit in Webern's short Langsamer Satz which he describes as surprisingly romantic if you're expecting a piece in the style of the dreaded Second Viennese School.
Here the challenge is working within a hushed dynamic scale, running from triple piano to piano. He's happy to reveal trade secrets, dropping his voice to an almost conspiratorial whisper, talking of the need for light bowing arms and an intense vibrato in the left hand.
And what could be more of a crowd-pleaser than Whakatipua by Dunedin composer, Anthony Ritchie?
"Especially its jazzy section," Fejer smiles.
"I'm sure it will grab the audience just as it grabbed us."
What: Takacs Quartet
Where & when: Auckland Town Hall, tomorrow at 7.30pm