Right now I have my friend's early black DAC-1 on my desk. I am using it with optical out of my Mac and into Grado HF-2. I love this combination.
To my ears, the clarity/linearity of the Benchmark matches well with the HF-2 which have great bass and are not as bright as my MS2i which I will sell over the Holiday break to fund purchase of HF-2. So they can handle clarity and higher end without being grating to me (with bowls).
I listen to a lot of electronic music or even current music that uses electronic instruments, so having clarity of source/amp with other amps or headphones down the line to color the sound is my current plan.
Right now I am trying to get a USB version of the DAC-1 because I plan to have it for a long time and would like to be able to bring it with a laptop to meets for others to listen to.
Since I have optical out of my computer and CD player the USB is not absolutely necessary for me.
Do know that the DAC-1 has been through some updates (I should keep a text file and collect the changes throughout the years) and that newer models use a newer headphone amp section called HPA2. (HeadPhoneAmp2)
I don't know what DAC-1 with HPA2 sounds like but with my limited experience, I am really enjoying my HF-2 right out of the DAC-1 with HPA1. I could see where someone listening to 70's rock or bright trumpet Jazz with bright Grados might really need a tube amp with DAC-1 but with my phones and music I think it is a good fit and I find it revealing without being fatiguing.
I did listen to another Head-Fier's DA-10 recently through his HF-2 but not with my electronic music. Because I did not do a direct comparison + with my music, I could not tell you definitively that the Benchmark was more linear or clear but from my reading many consider the Benchmark more "analytical" and some consider it even a bit bright or harsh.
What I am finding from meeting a couple head-fier's and what they listen to and is that they could use warmer components for what they listen to. For what I listen to, I want clarity and extension. As I branch out and pull all my old jazz and rock albums back out, I may be going for a tube amp later.
That's just my thought process. Also, I don't know if I would like using the volume rocker-arm constantly on the Lavry. I keep the benchmark right near my left hand and like the smooth pot on the DAC-1.
Good luck and share what else you learn on your search!
P.S. For example, I have enjoyed my IE8 dynamic iems (because they really extend low) and just picked up a special deal on TF10 balanced armature iems. I need low extension but like the additional clarity and speed that the TF10 and balanced armatures provide. I will probably keep IE8s for some music and listening experience and go up the BA clarity ladder as well.