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?