need help choosing budget tube preamp

hi guys, i need help deciding on a tube pre for my setup

dac: ps audio dliii
pre: ?
amp: mcintosh mc7100
speakers: b&w n805
cables: morrow/zu

i spent most of my budget already on the rest of my gear.. so i only have about ~500 left for the preamp, used is fine

another idea is to sell the mc7100 amp and get an integrated tube

any suggestions would be appreciated

thanks