I've used the SA700 and SP1000M quite extensively, but never the SR15 (aside from a quick demo at a CanJam last year). I haven't done a side-by-side shootout between the SA700 and SP1000M, but aside from the latter definitely being faster, my guess it is also slightly cleaner and more resolving. But there's no doubt that at the current US pricing, I'd recommend the SA700 every time. Sound is amongst the best of any "midrange" DAPs on the market and in my opinion, it's hands down the sexiest. Thing is drop dead gorgeous, especially in stainless steel.