Definitely spend money on a great preamp. It is essential for good sound. It's also the last place you want a bottleneck.
I had the privilege of owning a Zesto preamp and it transformed my system. More like transported it to another level. I've always spent more on the preamp in my systems and never had any regrets.
Do your homework on this one, your whole system revolves around the preamp. You don't want to make a lateral move.
Used can often put you in a component you could never have bought new.
New. I would check out lab12 pre 1