If you are big into headphones, then DAC-10H is the ultimate component to get. A lot of the cost of DAC-10H went into making it as clean and powerful as possible with incredible number of gain settings (for impedance matching with amp too, other than headphones). May be that's why a distributor sold like 40 units to recording studios in Cypress in the past 5 months. That's a lot of DAC-10H.
For DAC-9, we can do without the high power headphone amp and complex gain circuit, which also reduced the power requirement. So it is a "lesser" DAC in some aspects, but certainly not by design.