I currently can do 30.0x with the perks and the Shrouded Gloves.

Can I go higher then that?

Only if you "über"craft your daggers with the potion/enchant/smithing exploit.

x30 is the current max on consoles.

No, you can′t raise the multiplier any further. But the damage varies, depending on the base damage of your daggers.

I don't think you would need to go higher...

What exploit?

this, one-hitting ancient dragons should be enough for anyone

Craft some Restoration Potions, drink one, re-equipt your Fortify Alchemy items, repeat(x X), craft a potion that fortifys smithing and craft a sword with 13.000 base damage.

That still doesn't increase the sneak multiplier. 30x 13,000 is a lot more than 30x 42, sure, but it's still a 30x multiplier either way.

Damage is sneak multipliers * (skills+ perk) * (base damage + smithing improvement) * fortify damage enchantments.

And as other says with decent skill, perks, some moderate smithing and some fortify damage you can sneak kill everything in one hit.