Just to update for those that are interested, I replaced the Van Den Hul interconnect with an Audioquest Jaguar - a subtle but nice improvement, still not quite the level of resolution I am looking for. I'm going to spend a little time making sure that the arm/cartridge setup is optimal, then I will have a listen to a couple more phono stages. Stubbornly, I still think a new cartridge is a priority, but it is also the hardest to audition, so I'll keep an open mind on the phono pre. Any recommendations you guys have will certainly be appreciated.
In the end, I will likely stick with a dynavector cartridge of some type, since I like the overall dynavector sound, but I will listen to as many of the recommended cartridges as I can dig up.