Headphones powered by a preamp output?

The XLR outputs will not deliver significant power to the headphones. You'll need a headphone amp.

The Headroom Blockhead can be purchased in a balanced configuration, but you will need specially wired Senn 650s to listen to it. check out head-fi-org.

Thanks for the information. So a headphone amp is the way to go.

I'm interested in a Stax setup that has balanced inputs and uses tubes. Does anyone have any experience with Stax?

I am not sure that you have been given a complete answer.

With Krell preamps, there is plenty of power to drive most headphones. To use the XLR output, you will need an adapter. I am not sure if this is the best way to go, but it is a possibility.

Richard

I do it with my BAT VK-31se with pretty good results. You do not get super high volume and the highs are a little rolled off because the phones have a relative low impedance. Depends on your pre. The BAT has a pretty heathly output and has a single ended output as well as xlr. Recommend highest impedance phones (I use hd-600s, 300 ohms). Picked up an RCA to 1/4 stereo adaptor for the connection (radio shack). You problable will not find an XLR to 1/4 inch. You might need to get cardas xlr to RCA adaptors (female XLR to female rca).

Which preamp do you have?

Definitely worth a try.

With a Stax setup, the amp usually comes with the headphones. AKG K1000 comes with XLR cables.