Hi Kptseng,
Upon startup it is very normal to watch the bias wander a little as the dc operating points settle down during warm up. For measuring the bias you can do it two ways, both require opening the amp though. First with a dmm on the 200mv setting and measure the voltage drop across the emitter resistor in one of the output devices and divide the voltage drop for eg 14mv/0.22R a common value which would be 63.636ma, you can measure across a pair NPN/PNP but the first is easier as you can clamp one probe to the speaker jack positive, less chance for probe slippage

. I must also say, I strongly would recommend against the TNT article on raising the bias above manufaturer specs and Xover distortion from overbias can be just as bad and in many cases worse than underbias. The idle bias is often set at spec for a number of reasons, for some this has been found to give the best xover performance, for others, namely mid fi gear this bias is as so due to insufficient heatsinking and cost cutting to deal with the extra heat associated. But bringing it back up if it has drifted, to spec will improve imaging if it has drifted, dc offset seems to be quite high though, 500mv?, i would have that adjusted if there is a provision for it.. And as said by others, there must be no load connected, the only purpose for plugging in a CD player is to short the Inputs, no music need be played...
Colin