I can verify that Robben uses twin reverb and Zendrive abroad.
I was guitar tech for the Swedish Jazzfestival 2007, when Robben played.
(I even got to handle his old tele, 52 I think , not sure). He played that sucker LOUD!
We also experimented with some different pedals with Robben during sound check,
and the Xotic BB Preamp actually came close to the Zen with some tweaking.
The Zen had a meatier mid though, which suited the tele really well.
As for DUmble, I played one last time I was in Japan for Flaxwood
(actually with Kim Lerche, Peter’s younger brother! then PR Manager for Flaxwood)
Frigging sweet tone, but perhaps a bit overpriced (imo) the Ceriatone “dumble” would
work just as well for me anyways.