Hey Mo,
THRU on the Torpedo Studio (same with Torpedo Live and the VB-101) is full power, no attenuation is available for an optional cabinet.
There are two options to do that in our range of products, either plug in the THRU a Torpedo Captor and you get a -20dB attenuation (let's call it the affordable solution) or a Torpedo Reload (let's call it the best solution ^^).
Cheers.
GP