Considering the rather general nature of the opening question, I think you are simply going to get people recommending their favourite components, which you may or may not like.
Before spending anything like real money I would want to be quite certain that the recordings causing you trouble can actually be made to sound as you want them to sound. There really is no (practical) way to uncompress over compressed recordings and if their is no separation between instruments on the recording, not even the best system is going to sort them out.
Whilst there are some good rock recordings, I often find that most are poor in the areas you mention, separation, dynamic range etc. I deal with this issue differently, since I can not change these limitations I focus on the positive changes I can make. With this kind of material I focus on improving the presence and punch to enhance the 'live rock band' feel and get my enjoyment from this.
I would look at medium sized standmount speakers such as the Adam A7x or perhaps the A8x model if you have a big space. The A7x has a big, punchy sound and sound very 'live', they have a great transient response so sound 'dynamic', maybe this will help with your issues. They cost around £800 if you shop around.
Being active you can drive them off a streamer/pre-amp or a dac/pre-amp depending on what you actually need. For example a Cambridge Stream Magic (if you can find one) will do almost everything as will the newer and more expensive CXN, anternatively the highly regarded M-Dac could be used as a dac/preamp using an AEX and Bluetooth receiver as sources.