It is very easy to match a SS pre amp with a tube amp - electronic matching is not a problem due to high input impedences of amps and low output impedences of preamps. Its the reverse that can be problematic for some. If you don't want to have a tube pre-amp (which are much easier to maintain than a tube amp) go for the best quality unit you can afford, everyting else being equal, that has the features that you need, don't cheap out here, this is a critical component, and great units abound in the ads. Nothing wrong with Pass but I'd stay away from the Adcom - its not as good as your amp by a long shot.
amp-preamp considerations.
what are technical concerns[matching]when mating.have c-j prem.140 and am lookink for pre-amp.considering pass-lab x-1 or simaudio p-5.not stuck on either.using adcom gfp-750.looking for improvment on this.also new to tubes,think i would prefer ss.this amp is like having a small heater in da house.any input appreciated.