knocking

hi all,
my 2001 v70 auto in the last few days has developed a knocking when driving along which appears to be coming from the front drivers side wheel area. (although inside the car it sounds like the back!)I have had her off the ground and checked the wheel bearings which appear to be ok( no play and no noise when wheels are spun), I have checked drive shaft nuts are tight to 50nm and there are no stones in the suspension. The knocking increases pace with speed and is audible to people outside the car. before I spend a fortune at the garage does anyone have an idea where to look next? Drop links changed three weeks ago and noise does not lessen or worsen when cornering.
les