just to make sure, you dont get the sneak attack bonus when you power-sneak-attack someone? at least this has never worked for me (or the x-times-damage message never pops up or the enemies alway recognise you when powering-up for the p-attack)?

thx for a quick confirmation

I did this a few minutes ago. I killed a thalmore guard with a steel dagger power attack to his back without him noticing me.

Got a x6 multiplier.

hmm weird...i never get that

It works. I tested it. You can even get dual power sneak attacks for loloverpowered damage.

Maybe your armor is too heavy and you make too much noise.

I used the armor of the Dark Brotherhood; They have alot of stealth bonusses like making no sound and muffling anything. They also make you do extra damage when you backstab someone...