Guys, sorry for the newbie question, but what are normal and pro bias jacks? I recently acquired an SR-007 mk1 and is looking forward to purchase a BHSE. I know for a fact that SR-007 mk1 requires more power to drive than the SR-009, and that BHSE has two headphone outputs.
1. If I were to order a BHSE from Justin now, how will it be configured by default?
a) two Stax normal bias
b) one Stax normal, one Stax pro bias
c) two Stax pro bias
d) one Stax plug (which bias?), one Sennheiser (which bias?)
2. If the SR-007 mk1 were to be my primary headphone, what is the optimal way to configure my BHSE and which bias should I use? I read somewhere saying that one should always use the pro bias for SR-007 and SR-009, while others said the normal bias has a higher gain so the SR-007 should be used with normal bias. I also read that having normal/pro bias will result in a different sound compared to having two pro bias, even if I use the same pro bias plug. Which is true?
3. Does normal/pro bias have anything to do with the number of pins? The SR-007 mk1 and SR-009 are 5-pin, while older discontinued headphones are 6-pin. I don't think I would use a old 6-pin Stax headphone, unless Stax decides to release their next flagship headphone with a 6-pin.
4. Most importantly, just what is the exact difference between normal and pro bias, and why is this important?