I have 2012 Macbook air and recently I tried to compare Macbook air's sound quality with Clip+ and I could not find much difference
Is 2012 Macbook air's sound quality equal to iPhone 4s? Anybody get a chance to compare sound quality?
I have an iPhone 4S right now and I think it has a really good headphone out. While I currently own an Macbook Retina, I used to have the Macbook Air 13" 2011 model and I don't think it was as good - high noise floor and a lack of detail.
Noticing the differences really depends on what kind of headphones you have. I don't think you'll notice the difference with the Porta Pros (although I love those headphones) but you should if you use your HD-650 or the T70 assuming they can be driven to similar volume levels.
If you don't notice a difference, consider yourself very lucky. Enjoying the music is much more important than worrying if your source is "good" enough.