Optical Audio Outputs. Is there audible differences or are they all the same?

"Do i have to consider the "quality" of the output from the blu-ray player?"

Yes. The transport, like any other component, is very important to playback quality. Part of the quality is how you connect the transport to your dac. (I'm assuming you are talking about sound quality and you're using something like an Oppo or Marantz universal player to play audio formats like CD). I'm also assuming you're using Toslink and not AT&T ST Type. I see that I2S has been resurrected so I'll bring ST up just in case.

The most important thing you need to know about Toslink is that it has a bad reputation. And to be honest, the bad reputation may, or may not, be justified. It goes back to the 80's when CD was new. I don't remember the story word for word, but Toslink (Toshiba Optical Link) was put on some CD players as a digital out because Toshiba wasn't able to use the RCA SP/DIF (Sony/Philips Digital Interface) connection due to licensing issues. Toslink was always considered (by the high end community) as very inferior to sp/dif. Everyone avoided it like the plague until recently, because of HT becoming more mainstream.

The reason I'm going on about all this, is that people like myself, that have been into high end audio during the 80's and 90's, have a natural bias against Toslink. The minute someone mentions Toslink to someone like me, a little light in my head goes off. Sometimes I see the word Death light up, and other times I see Bose. There are a lot of people that have this natural bias against Toslink, and to be fair, I'm not sure if its justified. You need to know this because for all I know, they may have Toslink sounding great. Most of us have never given it a chance. 

Toslink has the advantage of providing complete electrical isolation. On the other hand, it is more prone to clock issues, mainly jitter. Which connection will serve you best depends on your requirements and the particulars of your system.

The reason I’m going on about all this, is that people like myself, that have been into high end audio during the 80’s and 90’s, have a natural bias against Toslink. The minute someone mentions Toslink to someone like me, a little light in my head goes off. Sometimes I see the word Death light up, and other times I see Bose. There are a lot of people that have this natural bias against Toslink, and to be fair, I’m not sure if its justified. You need to know this because for all I know, they may have Toslink sounding great. Most of us have never given it a chance.

wtf,

How does that happen? A guess manser has an account here as well.

"@mgreen27 .. despite your negative opinion of mansr, his post on that CA thread makes sense:"

Just to clarify, I wasn't singling out that quote specifically. I was just pointing out his overall method of communication. His primary motive in any conversation is to be right regardless of facts. If you challenge anything he says, he either ignores the comment, or talks and says nothing. "I don't know why you would think that.", "That's not what I meant.", etc... Stuff like that. He'll keep talking in circles while implying that he's right and you're wrong, and never give you a straight answer. I just don't trust people like that.