I would recommend a space tech Lab dac with a super rectifier. I have a space tech Lab dac and there is no hum with or without a preamp. If you go to Canuck audiomart you can read all the user reviews describing just what you are after.
DAC Under $3000
I am considering the purchase of a new DAC. Budget is no more than $3000. I lean towards clear, detailed sound with good separation. In the past I have had PS Audio Stellar, Benchmark, and Merason Frerot. I thought all were good, but not necessarily "special". Suggestions please. Thanks!