New to HF as a poster, but a longtime listener... :-)
I've just gotten my new DAC2, and it's pretty impressive. I listen mostly to HD800s through a DAC1-PRE -> Schiit Valhalla (I found the HPA2 to be just too clinical in combination with the DAC1). I've also not been able to let go of my Transporter ... using the smooth filter takes the edge off of bright recordings. I've even used the Transporter through an H1 (Benchmark's outboard version of the HPA2 with balanced inputs).
But now I'm listening to the DAC2 through its built-in HPA2 amp, and it is head and shoulders above any earlier combination. There's a sense of transparency and space, rather than over-analysis. Like my old Stax Omegas, a bit, but more dynamic.
Sometimes I've felt that the HD800s are too good at exposing the weakness of source components, and that's when I accuse them of being bright or too analytical. My experience with the H1 (outboard HPA2) in combination with other DACs bears this out. I have hooked the HD800s and the H1 to some high $$ DACs, and found them to be less strident than the DAC1.
Before, I preferred the DAC1 -> Valhalla to the DAC1's internal amp. With the DAC2, I find that using the Valhalla takes something away, and that the internal HPA2 does all the right things without ever making me want to turn it down.
I mentioned Stax earlier: I sold my SR-007 mk1 and 717 amp a few years ago. I loved the ease of the Stax setup, but I wanted the punch of dynamics (K701, then HD800). I missed that ease and musicality before today; now I think that I might have it all in one package.
I'm very, very glad that I bought this thing.
Sources: Benchmark DAC2, Logitech Transporter, Levinson 390S, DAC1-PRE
Amps: Benchmark H1, Headroom Micro, Schiit Valhalla
Cans: HD800, K701, HD650
Living Room: Classe SP-800, CT-M600, KEF Reference 207.2