Headphones (kind of urgent)

I just bought the Moog Etherwave Standard theremin. It will be in later this week. I need to purchase headphones, so I don't disturb anyone around me. I was looking at these:
http://www.amazon.com/AKG-K171-MKII-Headphones/dp/B0016MNB5M

Will these work for the line level output? They are High fidelity...if that matters at all.
Anything else you'd reccomend, around the 150 range

The line output is never strong enough to drive directly headphones. You will have to invest another 20$ for a headphone amplifier and 3$ for an adapter cable.

Oh, ok. I was wondering if the output was powerful enough. So something like this for a headphone amp:
http://www.axemusic.com/product.asp?numRecordPosition=19&P_ID=16256&PT_ID=243

Then an adapter from 1/4" phone jack to whatever that headphone amp takes for an input?

Thanks

This Behringer headphone amp is fine. But take care when choosing the adapter cable: The Etherwave's output is a 1/4" jack MONO output! The cable has to divide it up in order to serve both stereo channels at the amplifier's input. If not, you will only hear on your left ear...

This is getting more complicated than I thought. But I think I got it now. So Basic setup:
Etherwave Theremin -> 1/4" extension cable -> 1/4" Mono to 1/4" Stero (http://www.monoprice.com/products/product.asp?c_id=104&cp_id=10429&cs_id=1042907&p_id=7141&seq=1&format=2) -> the Behringer Headphone amp -> The high fidelity headphones (do they need to be high fidelity, or can they be any stereo headphones?)

Does this look right? Or am i missing a piece still?

Thanks

If the Behringer has a 1/4" input, then it will be ok. I couldn't find out if it has perhaps only a 1/8" stereo input...

Don't spend too much money on a headphone. I'm using a Sennheiser HD201 which costs about 20€ (=28$) on this side of the pond, after I saw that it was often used in semi-professional environments as monitor headphone and I'm very satisfied with it.

Oh right. That site isn't the best for specs. Here is the manual for the amp. HA400 (http://www.behringer.com/assets/HA400_P0386_M_EN.pdf)
So it says it has a TRS 1/4" input and 4x 1/4" TRS output. which will be fine with the adapter for the input.

Here is the extension cable I have in mind:
1/4inch (TS or Mono Phono) Male to Male 16AWG Audio Cable (http://www.monoprice.com/products/product.asp?c_id=102&cp_id=10244&cs_id=1024407&p_id=5497&seq=1&format=2)
not sure about the 16AWG, but it claims it is a 1/4" mono male to 1/4" mono male. So it should work.

Thanks for the info about the headphones. That will definitively save me some money. Already spent a bundle on the Theremin itself.

The cable is ok. But you have to take the adapter the other way round, so that it has a mono plug and a stereo jack: click me, but not so hard! ;-) (http://www.monoprice.com/products/product.asp?c_id=104&cp_id=10429&cs_id=1042907&p_id=7142&seq=1&format=2)

Right! I read that the wrong way with the link I gave. Yes, that is exactly what I need for the adapter.
I think I have a pretty good handle and what I need now to set this up properly.

Thank you very much for your help. Ill re-post later this week (hopefully I get it later this week, still processing at Moog) with how the setup went.
Cheers :)

You are welcome! Don't hesitate to come back here with new questions! ;-)