As to usage of "strain" in music, a quick search lead me to this article from the US dated 16 Feb 2015 [1] "When the trumpets blare and the snares rattle during the opening strain of John Phillip Souza’s The Washington Post March..."

I not proposing that Shakespeare is the easiest thing to read, but merely suggesting that it is not as inaccessible as it might first appear.

[1]http://www.miamiherald.com/news/local/community/miami-dade/h...

By the way, I found the "Spark Notes" for "If Music be the food of love". It's a dreadful lump when the poetry is gone, but here it is:

"If it’s true that music makes people more in love, keep playing.

Give me too much of it,

so I’ll get sick of it and stop loving.

Play that part again! It sounded sad.

Oh, it sounded like a sweet breeze blowing

gently over a bank of violets,

taking their scent with it. That’s enough. Stop.

It doesn’t sound as sweet as it did before.

Oh, love is so restless!

That, despite it's ability to encompass

as much as the sea, is impenetrable,

to anything, cannot be bought,

yet becomes cheap.

Even if fleeting, though, love is so varied and rich

that it is the highest pinnacle of experience.