@abnerjack I’ve also heard that running a quality delta/sigma DAC like your Benchmark through a tubed pre w/ or w/o a tubed amp creates positive synergy. Never had occasion to test it, though.
FWIW, I’m a bit of a DAC hoarder (an everything hoarder). I recently picked up a "gently used" (read so mint it looks brand new) Mojo Mystique X SE. I have it and the Lab12 receiving signal from the same DDC (Matrix Audio X-SPDIF 2). Intriguingly, that DDC outputs signal simultaneously on all 4 outputs. I have both DACs’ outputs feeding a very transparent, full-featured preamp (Bel Canto Pre3). This means I can very quickly and easily switch between these DACs in the middle of a music cut, just by changing which input is live on the output of the preamp. I’ve done some fascinating comparisons of these 2 decidedly high end DACs, one with that beautiful tube output, the other with an overbuilt, refined PS and no tubes. They don’t sound alike, but each one takes that great NOS digital sound higher than any other DAC I’ve heard.
At some point in the future I’ll also try 12AT7 output tubes with adapters in the Lab12 (I have a couple terrific matched pairs of NOS 12AT7s to do this with). The only problem with that is the adapter places the tube too high for the Lab12’s cover to fit, so I’d have to run it sans cover. Sacrifices, sacrifices!