Can a Sorcerer use the Silence spell and the Subtle Spell Metamagic to silently cast the Knock spell?

Question

The knock spell has a verbal spell component and states:

[...] When you cast the spell, a loud knock, audible from as far away as 300 feet, emanates from the target object [...]

I'm wondering if you can get around this loud noise by casting the silence spell, which states:

For the duration, no sound can be created within or pass through a 20-foot-radius sphere centered on a point you choose within range. Any creature or object entirely inside the sphere is immune to thunder damage, and creatures are deafened while entirely inside it. Casting a spell that includes a verbal component is impossible there.

You would ordinarily not be able to cast knock as it has a verbal component, but the Sorcerer's Subtle Spell Metamagic states:

When you cast a spell, you can spend 1 sorcery point to cast it without any somatic or verbal components.

So could a Sorcerer cast silence and then a Subtle Spell knock? Do these all combine thus letting you cast knock without the loud noise being created, or is there some interaction or rule I've overlooked? Does this scenario actually work?

Answer 1

You might not even need Subtle Metamagic

The Knock spell states that:

[...] When you cast the spell, a loud knock, audible from as far away as 300 feet, emanates from the target object [...]

As long as you are outside the Silence when you cast the spell, but the object itself is inside, the Silence spell will absorb the loud noise.

Knock has a 60ft range, so it should be perfectly doable to stand outside the Silence field and cast the spell into it.

Answer 2

This works

With Subtle Spell, you cast

without any somatic or verbal components

Thus this casting of the spell is no longer

a spell that includes a verbal component

Properties of a spell can change for given castings, the main example being its level, depending on the slot. Thus the spell can be cast.

This will also achieve the desired effect, as explained in this question and answer. Summarized, the sound is not created all over in range, but at the target of knock, radiating outwards from it. As that point is within silence, the generation of any sound is prevented.