Yes, I would have an Headstage Arrow now if they were available, but am confident the PB1 will be just as good though (doesnt really matter as I will never own a Arrow now so I wont know!).
My PB1 Toucan arrived today, very very impressed with Ibasso as a company, very fast delivery (from China) and very professional in their email responses (Robert - Headstage take note!).
In the end I just ordered a USB DAC cable from headstage, which to their credit has been shipped now. I am more than happy with my PB1 though, much prefer its volume knob too, rather than the Arrows dial.
Form factor it fits my fuze pefectly - just a shame the fuze doesnt have a lineout, not so great with my s:flo2 (shape wise) though. But wont be amping either of these long term.
Will try it on my K601's tonight off my laptop, which will be its new home (my fuze doesnt really benefit from an amp with my travel phones).