Sean Dyche estimates he has made 500 phone calls this summer as he attempts to create a squad capable of staying in the Barclays Premier League.
Dyche led Burnley to promotion from the Sky Bet Championship in May despite the Clarets having one of the smallest squads in the second tier.
He has so far added goalkeeper Matt Gilks, midfielders Steven Reid, Matt Taylor and Michael Kightly and forwards Lukas Jutkiewicz and Marvin Sordell, but hopes to boost the numbers further before the end of the month.
Dyche, who refused to comment on reports linking the club with Nottingham Forest midfielder Henri Lansbury, said: " It's a challenge.
"Some of it is intriguing to know what's out there, what we can do and what we can't do, and it's annoying sometimes because there's things you want to get pushed through and they drag and drag and drag, and we've had that on a few different situations.
"We work hard. I reckon I've made 500 phone calls over the summer to managers to agents to coaches, background on players etc. And that's just me, that's not counting my staff, the recruitment side of things.
"We keep looking and we keep searching for the ones that are appropriate and that can help us to enhance our chances of doing well this year.
"We need more strength in depth but that doesn't just come with anyone, we have to also make sure there's some quality and talent there otherwise it would be counter productive.
"There's not a definitive number. I doubt we'll hit 25 senior players, but we definitely want to enhance the numbers.
"If we had the finance we're spending now in the Championship, that would give us a real competitive edge. In the Premier League, we all know what it's like. The numbers are vast, e ven for players who you wouldn't recognise as being market leaders, but they move for very big fees and very big wages.
"You could get frustrated by it but what's the point? That's not going to get any deals done.
"The only over-lying marker that usually gets any deal done is money, we all know that. We will put good resources into certain areas and certain deals, but there is a limit.
"The club's future is important, not just the immediate future on the pitch."
Burnley are arguably bigger outsiders than they were when they reached the Premier League for the first time in 2009, a stay that lasted only one season.
They begin their campaign by welcoming Chelsea to Turf Moor a week on Monday, allowing 'the Ginger Mourinho' to pit his wits against the real thing.
Dyche knows his team will be written off before they have started but he is confident they have the right formula to surprise people.
"We were underdogs last year and I think we got used to that," said the 43-year-old former defender.
"It can bring freedom. There'll be an expectation from us, how we perform and how we go about it, but from the outside arguably we'll be deemed probably one of the biggest underdogs there's been in the Premier League for a while.
"But we do know the underdog story. There's not many, if you actually analyse underdog stories, that are by chance or luck.
"So at the same time as being an underdog, we like to think there's a way we go about our business that will give us a chance to do well and be competitive and win football matches."