Best DAC to also use as a preamp

EAR DAcute 192 is superb as DAC and preamp. Has two tubes that can be rolled for change of sound. A very musical, Non-digital sounding DAC.

The PS Audio PWD, is a good option.
You can also consider the Direct Stream, little over your budget tho..

Benchmark Dac2.

"I happen to have a demo Overdrive SE I'm willing to sell."

How convenient.;-)

"I used remote control at Newport froman iPad. All player software has digital volume and you only need about 9dB with an Overdrive to adjust for all tracks."

Maybe he doesn't have an iPad or maybe he does want Wi-Fi
polluting his listening room.

I don't know anyone who would pay $6399. for a DAC/Pre
without a remote.

I would if if sounded as good as the unit in question!