Markbass is normally very mid heavy and cuts through the mix just brutally. They do sound pretty bland if played without a band, do not let this impression turn you away if you are into a mid present bass tone. Some of their amps have a filter that turns the trademark midrange tone into a scooped sound, i think it's called VLF/VPN Filter or something like that. One turns the sound more vintage (damp and wooly) and the other scoops the sound, just like the contour filter on the GKs.
That would have been my best bet on that sound, a GK1001. It can get very clicky and still maintain beastly lows. Most of their other Amps have too much growl for that type of sound.
After checking out the GK1001 you mentioned, I'd say I agree with you. That tone that he's getting seems very similar to the tone I've seen others getting with their GK amps. Thanks!

