If you have a low impedence headphone or IEM and used high gain you would probably get distortion.

However, if you used high gain and an EQ and reduced the gain output on the EQ side you might get better results.

When I get anything new I start at a low gain setting and adjust from there. Once I find the sweet spot, I just leave it.

Almost all my IEMs use low gain. High Gain I only use for headphones that require extra power.