Ok to use a Shunyata Hydra A-4 with a VAC 70/70?

The Hydra A-4 is a passive conditioner, rated at 20 amps. It will not keep power "sags" from entering your VAC 70/70 amp and pre-amp. It will handle the current draw of both components. A dedicated line would be the first step. You would have to let your ears be the judge of the possible sonic benefits of the A-4. Be aware that the quality of the power cord going from the wall to the A-4 will play a big part in the overall sound of the system.

I'd call an electrician first. Anything else would be like using a bandaid on a wound that needed stiches.

Assuming there is nothing wrong with your electric, as Rhljazz suggests, I would get something for the preamp but probably not for the amp. Although, if you get the Hydra, you can try it both ways. I have a 30/30 and it goes directly into the wall. Also, since we are talking about power sags, a regenerator may be a better choice. If you call Cable Co., they have all of these products to lend out so you can try them in your system first, before you buy. I use them all the time for stuff like this.