Dumb Head Phone Question


I am looking at a pair of Sennheiser HD 700 or B&W P7 headphones that are available through my company's rewards program.

They would be mated to an Oppo 105 and W4S ST1000 amp.

The dumb question is will I need to buy a head phone amplifier?

If the answer is yes, what technical details do I need to take into consideration?

Also, I would welcome any comments regarding the head phone choice.

Thanks!
dsper
Also, The Oppo does not have a amplifier inside it to drive headphones. It has a 1/4 inch jack so you can plug a set of headphones into it, but it will not drive a pair of high quality HD700's you need a external headphone amp.
I don't get it. If there's no amp at all, then the jack is useless. Why put it there?
This is from the Oppo 105 product page:

"For a more intimate listening experience, a pair of headphones can be connected directly to the BDP-105’s built-in headphone amplifiers. The headphone amplifier is connected directly to the ESS Sabre32 Reference DAC and offers a unique performance advantage over standalone headphone amplifiers."

Looks like they do indeed have built-in headphone amps like I stated.

Here is the full link.

IIRC, almost all of the reviews stated that this wasa pretty decent headphone amp.
Mofi is correct, as usual, certainly with respect to the 105 having a reasonably hefty built-in headphone amplifier. (I have no knowledge of its sonics, but based in part on his comments I'd expect it to be pretty good in that respect also).

As indicated on page 85 (pdf page 89) of the manual, the 105's headphone output can provide 63 mW (milliwatts) into the 150 ohm impedance of the HD700, which is way more than enough for anyone who isn't interested in having their hearing damaged. (Based on the 105 db/1 volt sensitivity and 150 ohm impedance of those phones, it can be calculated that 63 mW will drive them to an SPL of about 115 db).

There's no spec for the 105 corresponding to the 22 ohm impedance of the B&W P7, but the 105's output rating of 187 mW for a 32 ohm load would seem to indicate no problem at all in that case either (although I'd be hesitant to choose phones having significantly lower impedances than 22 ohms, given the lack of ratings into low impedances).

So the answer to "will I need to buy a headphone amplifier?" is no. Although it is not inconceivable that you might eventually PREFER to buy a headphone amplifier.

Regards,
-- Al
Thank you for the reponses. It sounds like the Oppo will do at least to start and, just like everything in audio, it can be a journey.