headphone amp power speakers

That depends on the headphone amplifier.
Some, like my β22, can power both headphones and speakers..

but i guess that most of the headamps out there won't handle speakers right...or will make them sound a little weak and powerless. right..?

Pretty rare, I think. There's also an old Eddie Current model, some beta 22's. I think the power levels are too different. More common to see headamp/preamp combo's.

Aren't the A5s self-powered? IIRC, they have an internal amp.

As for your question in general, it depends. There are two factors:

1. How much power a headphone amp can output, and

2. How much power the speakers need.

There are a few other factors, but let's talk about these because they're most relevant.

First, headphone amps don't always output much power. I think the Gilmore Lite gives you about 1W. Some output more, but you don't need much power for heqdphones.

Next, keep in mind that speakers are a type of electric motor. You need to have a certain amount of power to move that motor. In a dynamic driver, you have a voicecoil, which is a coil of wire, a cone that the voicecoil is attached to, and a magnet. You put power from the amp through the voicecoil, which creates a magnetic field. That magnetic field interacts with the magnet, and that pushes the cone back and forth, making sound.

So, it depends on the strength of the magnet, weight of the cone, and how much power the voicecoil needs. If these things don't need much power to work, then the speaker is very efficient and can be driven with very little power. However, most loudspeakers, including bookshelves, need more power to operate than a headphone amp is designed to deliver.

If you want to look at highly efficient speakers, look at the big Klipsch horns and Lowthers. Both of those will run from a Gilmore Lite.

On the other hand, typical dynamic loudspeakers like the ProAc Response 2.5 clones I built need more. The ProAcs are happy with around 40W-50W input. So you can see why 1W from a Gilmore Lite would only produce sound at whisper levels on them.

Anything that can adequately power K1000s should be able to handle certain efficient speakers. Remember, some speaker amps only put out like 2W. But we're generally talking big horns, single drivers, and other really efficient designs. Headphone amps won't be able to handle small multi-driver things like monitors. Well, maybe if you made a beastly 50W B22...

Off the top of my head, the following have or can have speaker outs:
ZDT
Woo 5
Yamamoto HA-02
Beta22

Anyways, cheap bookshelf and computer speakers generally have amps built in, so they don't need power.