I can't figure out the impetance and power issues exactly work for headphone matching with The BFP (see tech details below). I thought best to just ask if the higher pro headphones will work without an additioanl external headphone preamp?

I want a good quality open-back set of headphones for editing and mastering, but can't work out if I need an additional heaphone amp for the BFP, to get the full benefit of the better headpohones.

I record with a closed-back Sennheiser HD280 Pro, which must be ok, because the impedance of those is not so high (impedance 64Ω).

But what about the Sennheiser HD 600 Open-back Audiophile / Professional Headphones (impedance 300Ω)?
And what if you go even higher, up to 600Ω?

On the BFP specs, the larger 6.3mm headphone jack is for high impetance headphones, right?
And, Where is the point that a low imptance headphone become a high one? 50Ω?100Ω? 200Ω?

Questions to understand the specs:
1. Output impedance: 10 Ohm (That seems low? I don't understand, is it short circuit protection, or something?)
2. Output level at 0 dBFS, 1 kOhm load: +13 dBu (Looks like a maximum volume/load? does the 1 KOhm load mean it can handle way up there like to 800Ohms headphones? Or is to tell you some pother thing?)
3.Max power @ 0.1% THD: 50 mW (The HD600s require 10 mW, which is way less, is that the way to read it?)

Thanks for anybody's help. I know there are a lot of questions, but any that you answer would be appreciated.
Warwick