After living with the 2Ce Sigs. for a while, I would think about 85db on recordings with a lot of deep bass is about it. This is in a smallish to medium room (15x23) If deep bass is not there, then they will play louder. To be honest, these speakers are not designed to be rock speakers. You need high efficiency speakers for that which the Vandy's are not. Vandersteen has a comprehensive explanation in the owners manual about this. It is not so much volume as it is how long that volume is sustained.
The Vandy's due require a lot of amplification watts. I agree with the above statement of at least 150w/ch. Also, these speakers, though fairly easy to drive, due have a low impedance dipping to less than 3 ohms. They do like current!
As far amps, the ST70 is out. If using tubes, you need something at least in the class of an ARC 100 mk.II or III (solid 100w/ch) Of the ones listed, I'd go with the Stratos.
If I was going to "Rock" with Vandersteen's, I'd use a pair of 2Wq matching subs.