Well Pete, your ML 335 has an input impedence of 100K ohms, so you shouldn't have any impedence matching issues with any preamp that you choose.
Now when you say that it must have XLR in and out, do you wish the preamp to be a differential topology (balanced internally)? If so, you're probably looking for a BAT, ARC, Cary or Atma-Sphere, depending on what flavor you are looking for.
If you are just looking for XLR in and outputs, but don't care about balanced topology, there are other choices like VAC, Lamm, Modwright, again depending on what flavor you are looking for. By flavor I mean are you seeking to head towards resolution, or towards musicality? They are seperate paths. Enjoy the journey.
Now when you say that it must have XLR in and out, do you wish the preamp to be a differential topology (balanced internally)? If so, you're probably looking for a BAT, ARC, Cary or Atma-Sphere, depending on what flavor you are looking for.
If you are just looking for XLR in and outputs, but don't care about balanced topology, there are other choices like VAC, Lamm, Modwright, again depending on what flavor you are looking for. By flavor I mean are you seeking to head towards resolution, or towards musicality? They are seperate paths. Enjoy the journey.