I agree with you on speakers. However, I've also read that the difference between a $1,000 DAC and the DAC in an iPhone is indiscernible.
What is important to remember is that all ears/brains are not the same. I have 0% doubt that there are people out there that have the ears and brains that can hear a difference between different audio components because they simply train themselves to do so. Being an audiophile is their passion, and they are truly good at it. They ALSO listen to a "standard" album or albums that they have trained themselves to hear. They WILL be able to discern things that 99.99% won't be able to do, but some do also claim more than they are capable of.
Also, an orthodox audiophile wouldn't listen to an MP3 or CD, much less metal music, so I don't relate too well with them in general. Because they take their "craft" so seriously, I do respect their opinions about some things, though. You just have to be careful and use your best judgement and common sense.
I own a set of Klipschorns and a Belle Klipsch I use as a center. Those speakers are rather expensive to just fork out at one time (although I got a very nice deal on them) but I likely will NEVER have to buy another set of front and center speakers barring my house catching on fire and my family not already out of danger ^___^
AS far as DAC's...... ehhhh..... it is apples and oranges. My Oppo DVD player can play SACD and DVDAudio etc. etc. Your IPhone doesn't play those, or even a redbook CD. Your iphone decodes MP3s and FLACs (I think that is what the Apple compression is called.)
Having said that, I don't feel like having an iphone decoding an MP3 would sound any different than having some audio component do it. My opinions are mine alone, but I can guarantee you that they are based on quite a bit of both personal listening and objective study of diverse internet resources.