Preamp vs. headphone amp


I would like to know if it's common for quality pre-amps (from early 90s) to drive headphones properly, given that it has a headphone output. That is, can I do headphone listening with just a CD player and pre-amp? The sound quality I'm looking for has to be at least comparable with that of entry headphone amps like the Creek OBH-11 or Musical Fidelity X-Can v2.

Also, what exactly is output inpedence? I'm looking at an old SimAudio pre-amp that has an output indepence of 100 ohms (the Sennheiser HD580 has a nominal inpedence of 300 ohms).

Last of all, how has pre-amps improved over the past 10 years? That is, can any quality 10 year old pre-amp (>$1000) still compete with today's entry level ones?

Thank You.
My Aleph P drives my Senn HD600 beautifully.
I can only speak to the headphone amp incorporated in the Sonic Frontier Line series preamps with Headroom circuit.
I am driving a pair of Grado RS 1's easily. An exceptional combination.