What tubes does this use? I ask because tubes have a distinct personality and I might be able to suggest a substitute.
Isolation is a big deal on the Audio Note DAC. Have you tried Still Points or Symposium Roller Blocks under it?
I also suggest putting some weight on top of the Audio Note. Begin with a large book, if that helps you can make a permanent load from a flat plastic container with tight lid (like you see for fish lures) and fill it with sand or lead shot, depending on the amount of weight needed.
Only other issue, you mention comparing sound between Audio Note and your Sony by switching your preamp. Unless the interconnect cable in these two positions is identical, you may be auditioning interconnect as well as DAC performance.
Isolation is a big deal on the Audio Note DAC. Have you tried Still Points or Symposium Roller Blocks under it?
I also suggest putting some weight on top of the Audio Note. Begin with a large book, if that helps you can make a permanent load from a flat plastic container with tight lid (like you see for fish lures) and fill it with sand or lead shot, depending on the amount of weight needed.
Only other issue, you mention comparing sound between Audio Note and your Sony by switching your preamp. Unless the interconnect cable in these two positions is identical, you may be auditioning interconnect as well as DAC performance.