Looking to upgrade my preamp, suggestions?

If you want used, my BAT VK51SE originally sold for $9k, but I see them go for just about your $3500 budget. It would have nice synergy w/your amp. I've considered replacing it a couple of times and just couldn't find anything that suited me more without spending a boatload. The solid metal remote, mono switch, polarity switch, programmable name display, and programmable volume for each input all combine to make it very convenient. I always like to think of myself as someone who won't sacrifice sound quality for convenience, but I must admit these features are useful and nice to have.
If buying new, I strongly suggest checking out Backert Labs preamps. They sound amazing, are a tube roller's dream and offer great value. If I ever make a change, that's the first brand I will consider. Cheers,
Spencer  

@sbank 
yes the vk51se is also on my hotlist, although as it only has balanced inputs i was considering the vk32se more just for convenience
however i know bat make the xlr to rca adapters so always a way round things

Yeah, keeping that big amp of your close to the speakers with short cables and running longer balanced interconnects to the preamp on the side of the room with the source gear is the way to go! Cheers,
Spencer

Take a look at audionet pre g3 I have the same pre and it is a outstanding . There is one on here now