Learn Spanish (Latin America): Él compró no solo unos audífonos nuevos, sino también un micrófono. - He bought not only some new headphones, but also a microphone.

When you want to say "not only X, but also Y", Spanish uses the set phrase no solo X, sino también Y. We use sino instead of pero here because the first part of the phrase is negative (no solo) and the second part adds information to contrast it.

The lesson mentions sino que también. Why don't we use que in this sentence?

You only add que when the second part of the sentence has a new conjugated verb. Because un micrófono is just a noun phrase without its own verb, we just use sino también. If he had done a second action, like "but he also rented a microphone", then you would need sino que también.

Could I say pero también if I drop the no solo?

Yes! If the first part of your sentence is affirmative (not negative), you use pero. For example, you could say: Él compró unos audífonos, pero también un micrófono (He bought some headphones, but also a microphone).

Why is it unos audífonos? The English translation just says "new headphones" without "some".