I wrote an email to the support, no answers yet 
"Dear Crate team,
I have a few questions about putting loads to the Powerblock.
1. Can I run the unit safely via headphones without attaching anything to the speaker inputs at the back?
2. Can I run just one speaker at one of the 4 ohms inputs, without having anything attached to the other 4 ohm input?
3. What exactly means depressed? I'm sorry if that sounds weird, but I'm German and not familiar with that type of explanation? Does it mean if the pin stands out more or less?
Thanks in advance for answering my questions, too bad the product is discontinued. It's awsome.
Regards, XXX"
Maybe someone has the unit and can help me out.

"Dear Crate team,
I have a few questions about putting loads to the Powerblock.
1. Can I run the unit safely via headphones without attaching anything to the speaker inputs at the back?
2. Can I run just one speaker at one of the 4 ohms inputs, without having anything attached to the other 4 ohm input?
3. What exactly means depressed? I'm sorry if that sounds weird, but I'm German and not familiar with that type of explanation? Does it mean if the pin stands out more or less?
Thanks in advance for answering my questions, too bad the product is discontinued. It's awsome.
Regards, XXX"
Maybe someone has the unit and can help me out.
