They said High Impedence headphones that are 250 – 600 Ohms are best for studio and getting an overall balanced sound.

The low impedence headphones 80 or less in Ohms are more for private music listening. Also, the amps for gaming will have bass boost or gain options.

And I noticed they called the amp I bought a class A.

The second 70 some amp was claimed by a user review to pair well with mine. I figured I would do the budget one for now to see if it is all I need. Less money better.

Also, one type of amp has a power supply type input, another type uses USB and some even charge on laptops or with a power supply usb adaptor to plug in the wall.

That is enough information for me. Haha

Headphone Impedance Demystified: Do I Need a Headphone Amp?