Need Preamp Pass XA60.5 and Dynaudio C1 mkII

Seriously need your input guys. I need a preamp to mate with my Pass XA60.5 and Dynaudio C1 MKII. Really need some ideas on preamp. My budget is about 6000, prefer used.

I'm hoping to bring my sound a little more forward presented with better imaging. I came from a old set of B&W 705 and that set had one of the best imaging I've ever heard.

Currently using a Rotel RA-1520 as preamp, so it needs to go. Must be fully balanced, I plan to run it in XLR config to bring out the best of the Pass. The only real preamp I heard was Simaudio, can't remember which model but was told its a lower end model (350p?). But really sounded amazing with my setup, but what else is out there?? Also if I do go with Simaudio, which one do you like? 740p? p7? p8?

Have anyone experience with this combo and a Classe CP-800? I listen to music on a computer also, so having a USB DAC is a bonus.

Thank you very much.