whats ur budget?
ok, for under a grand:
above all, audio by van alstine transcendence 10 RB also known as T10. get it from frank van alstine for a grand, or get it used. fantastic headphone feature. i think theres one on fleabay fight now that the guy keeps relisting. you can prolly get it for a fair price. itll drive ur amp just fine. quality at this price point is off the chain. add a fantastic phono stage for $379 avahifi.com
bottlehead moreplay or foreplay. everyone loves it. comes as a kit new but very budget used. high output impedance by modern standards. dunno what amp to pair it with, but everyone likes this. i reckon will want an amp with very high input impedance, tho i dunno how much.
rogue audio. folks really dig the rogue audio tube preamps
used gear under $1000:
the clasic: a restored dynaco pas-3 or 3x. unmodded its a lil noisy, and youll need an amp with at least 100k in put impedance. a cheapo is adcom gfa 535. the good one is only gra-535.
scott and fisher got some great tube pres with good phono sections.
quicksilver but i cant remember the name Audible Illusions Modulus, but i think its hybrid.
Anthem PRE 1L right now on fleabay. IIRC these are "warm but good."
bottlehead moreplay/fureplay
best of luck!