Am i benefited from using a headphone amp ?

The short answer is yes, you will certainly appreciate the difference between a dedicated head-amp, and the op-amp on the head section of your integrated. Whether it is worth the investment is up to you. I have a Portal Panache, that has a reputation of having an excellent headphone stage, which it does. Yet I much prefer my cans amplifed by my Berning Micro-ZOTL. It is smoother, easier to listen to in every way, more holographic and natural sounding. Just like any link in the chains, synergy is something you should be considering in choosing an amp for your headphones. I'd research your particular headphones and see what others like with them. I'm using Sony MDR3000's which are quite different from your Grados. Headphones are pretty unforgiving, as you can imagine, you hear every nuance. If you plan on listening allot to phones, the head-amp is a good idea. If it is just a secondary, occasional distraction, the integrated amp may be all you need.

Marco

I was in the same boat as you are with exactly same amout to spend on a headphone amp to drive the Sennheiser HD580.

Here is my story.......

http://www.audioasylum.com/cgi/m.pl?forum=amp&n=75506&review=1

Do some research at www.head-fi.org.

(Sorry about your wallet.)

ttboy,
there is no doubt in my mind you would recognize a superior level of musical satisfaction with the use of a headphone amp!
there are many, both tube based and s.s. to choose from, some with built -in dacs ranging from just under your pricepoint to several thousand.
check first to see if you need all the "bells and whistles" that are offered then goggle "headphone amps" and you will find many companies to review.
good luck!
azjake
p.s. there are several good "used" models out there at reasonable prices too!