Please also suggest some more dacs under $2000 with external switch for voltage conversion.
Not only that Benchmark DAC2 has switching power supply but also
has many of them inside. It uses main +12V switcher and then
DC/DC converters to create +/-18V. I don't know of linear power
supply that can operate from 88 to 264 VAC without any switch and
at the same time to be able to operate up to 373VDC.
Look at the picture - perforated metal box in front is Switch Mode
I had asked W4S along time ago for the DAC2 which i bought.
The DAC-2 requires a power supply pin configuration change. Contact W4S directly. I was told that they can supply a power jumper that can be used to reconfigure it for one of the voltages, and be left out for the other. I have not done this but best bet is to double check with them. At least those designs were changeable if you open the cover and get the new jumper.
According to Benchmark Technical Director John Siau Benchmark was designed purposely not to sound warm but neutral instead. Warm sound works wonderful with voices or guitar but not so great with instruments that have more complex harmonic structure like piano or percussion instruments. Overly warm gear can, according to John Siau, make piano sound like out of tune. Benchmark is very smooth and resolving. Because of that it can reveal deficiencies in the system. It revealed bright sounding aluminum dome tweeters in my previous speakers but sound wonderful with my current speakers that have well implemented soft dome tweeters.
I have been researching DACs with Dual power capability for a while.
Here are some candidates I found.
Chord Qute HD
Wavelength DACs (any model, I own the cosecant, that you can find used for around 2000$)
Auralic Vega ($3500) can be switched easily according to distributor.
There are others but they are more expensive.
AMR DP777 comes to mind
Hope that helps