I own a pair of PSB M4U1's (which are fantastic), but when I was performing my various listening tests at the store before I purchased them, I couldn't help but marvel how the PSB M4U2's integrated amp funcitonality made them come alive when switched on. Hence I've decided I'd like to get an amp for my M4U1's.
I don't want to spend too much, so have been looking primarily at the FIIO E07K, E11 and E17. I am aware that the E07K and E17 also include a DAC. Obviously with my iPhone 5 I'm stuck using the internal DAC so in that respect its just a comparison of the amps, but a large portion of my listening will be via my new Retina MacBook Pro.
Does anyone have any information as to how good the inbuilt DAC and headphone amp are in the current MacBook Pros? How much better is the DAC in the E07K/E17 and is the difference enough to notice? Also, (and I may be displaying some ignorance here) if you were to simply plug a headphone amp in to the headphone out on the MBP, you are double amping right? Given there is no line-level out on a MBP, would using USB audio out and hence skipping the MBP headphone amp mean a better sound even if the DACs were equal?
In the end my question boils down to this: what is going to get me the best overall sound out of my MacBook Pro and iPhone with my PSB M4U1's, the E07K, the E11, the E17, or something else? If its something else, I'd ideally like it to be available for purchase in the UK and be less than £100 (or thereabouts).
Unfortunately there is nowhere in London I can try out these amps so I have to rely on the word of people on forums like your good selves.