So I have been researching headphones and headphone amplifiers as I am unable most of the time to let my Axioms loose due to a new member of the family. (worth it by the way). But I do miss listening to my audio at reasonably high levels.

I have my headphones picked out but I can't seem to get any solid information on headphone amplifiers for home systems.

Question: Is there sufficient output on the typical home theater receiver for headphones or would an amplifier be required for optimal output? I couldn't find any specs for my Onkyo 601 with regards to the headphone output. Are these headphone amps only necessary for the pathetic output of most of today's portable machines? Or would one add significantly to a home system?

SS, this question is mostly determined by the sensitivity of the headphones in question, which is in turn mainly a matter of the impedance of the phones. Those with very low impedance(e.g. 30-40 ohms)can be driven easily even with portable players; those with impedances much over 100 ohms might need a separate headphone amp. I occasionally listen on my AKG 501s, which are rated at 120 ohms, but still have plenty of volume with my regular receiver phone outputs. You don't mention which phones you're considering, but for example the excellent Sennheiser HD-595s, which are available around $170, are rated at 50 ohms and should be easily driven by your 601.

Yes, which cans have you chosen? With my high-z Sennheisers (300Ohms) the receiver outputs I have used have been only minimally effective in bringing out the dynamics of the music. With lower-z cans this has not been a problem. I have a couple of head-amps for iPod/PCDP use and for listening through the receiver. You can go from $20 BYO/DIY amps to $$thousands$$ as far as the headamps go. Headroom makes some good amps over a wide price range. I think the real value is in their mid and low-midrange models.

Congratulations on the new addition!

I'm surprised that the wife will let you listen to your music as the baby cries. LOL!!!!!

I was going to go with the Sennheiser 650. I figure if I can get them for around $350 that it will be a good investment. The way I see it I spent more for just my center channel so...
But I don't really want to have to buy a seperate amp to listen on my home system.

Ssutherland, when I use my Senn 650s with my HK, I turn the volume somewhere between 30-25. They like a lot of power. Normal listening levels with speakers finds the volume at 40. To me, the Senns feel kind of flat with the receiver headphone output and I catch myself upping the volume to dangerous levels trying to attain some kind of dynamic response. I've read that some receivers don't put much into the power supply part of the headphone output. I don't know if this is technically true or not. On an interesting note, I have a tube preamp which is supposed to have a beefier headphone section. All I know is that I don't have to turn the volume way up when I listen to the Senns. I'm thinking the preamp does offer more power, and the sound is very dynamic to my ears.

Again, I don't know the techinical aspects of it, just giving you my thoughts.

SS, since the 650s have a 300 ohm impedance, it's questionable(don't know the 601's headphone output)whether they would be driven to a satisfactory volume(but careful about your hearing). Again, the 595s, with a 50 ohm impedance, might be a better choice.

As an edit, my understanding is that generally the receivers have no separate headphone amp, but rather they simply insert a resistor or some voltage dividing circuit to reduce the output of the amps to the milliwatt range suitable for headphones.

The 650's are unbelievable headphones. They are my preferred cans for "listening in the dark." It would to you well to invest in a headamp with those. As mentioned above, you can find yourself pushing the headphone output of your receiver awfully hard trying to make the 650's sing. Plus with a headamp you can run an iPod or PCDP or even a computer audio output through the amp to your headphones. None of those devices can do much with the 650's alone (or any 300 ohm cans for that matter).