The heatsinks on first amp, i added them. It originaly came with no heatsinks anywhere. I used same 3 ohm speaker in both cases and in both cases i used 24V. I know this is bad for amp and speakers, i simply wanted to measure them. The ZK-502L will play a lot louder, draw more current and also there will be a lot less clipping. I will try to read which chip is on ZK-502L because so far i am VERY impressed. Also its kind of amazing that it came with no heatsinks, but came with added things. The one i already got cost 6.5 bucks and i just ordered another one for 4.5 bucks. This is a total steal and will be great for my DIY speakers.
**broken link removed**