Yes, if you're using high-impedance cans. 600's are.
I have a couple of headphone amps. I have a PA2V2 and a Little Dot MKII (tubed). They are both very good, but the Dot is incredible.
The Dot lives at work with a pair of Sennheiser HD-650's. I absolutely love the setup.
If I connect the HD-650's to a 'normal' headphone output, like an iPod, iPhone, or my home AVR, they sound ok, but they definitely lose something. Bass is lacking, and the overall sound is just sort of drab. I owned them before I bought the amps, and was very close to returning them because I just didn't see what the fuss was about for the $$$. But when connected to the Dot, they absolutely come alive. Bass is strong, powerful, and extraordinarily clear. Highs are clean and very smooth. While no match for a speaker setup, a surprising amount of spaciousness and depth also appears. The realism is intense; close your eyes and the musicians are *right there*. It's almost too good to listen to at work, as it's very easy to get pulled into the music.
I also briefly had a pair of AKG-701's to play with. They were of somewhat lower impedance than the HD650's, but they quite need good amplification too. I also had a Headroom Total Bithead for a couple of weeks but returned it. I wasn't all that impressed with it for the price and had big problems with GSM cell-phone interference. That's a problem for a lot of electronics, but that Bithead would pick up that GSM signal (dit-dittty-dit-ditty-dit-ditty-dit) if there was a cell phone within 15 feet of it.
As Wid said though, with some cans it might not matter. I have a pair of Grado SR-60's (which are absolutely fantastic for the price) and they really don't sound any different if I use either of the amps vs. just plugged into an iPod, iPhone, etc.
See
http://www.head-fi.org for all kinds of madness on the topic.
