Good. Take your time and be convinced that these speakers or similar will cater to your listening preferences.
Imaging/soundstage is the ability of the system (mostly speakers) to create the illusion of a properly set soundscape.
When this is "acceptably" achieved, most people feel "Ah! This sounds right to my ears. I like it"
I say "acceptably", because there is no perfect universal speaker/s (+system) that appeals to everyone equally.
Dynamics is the ability of the speakers (+system) to reproduce quiet and loud passages in content effortlessly.
Also, a decent transition of sharp notes, start/stop and "accuracy" of tone makes music listening a pleasure or nightmare.
Bass control:
This is a very tricky subject. Every kind of music has bass notes. This helps anchor the overall ensemble of music (and instrumentation).
If bass is weak, the other instruments gain prominence and sometimes spoil the presentation.
If bass is strong, it may overpower other instruments or minute details and again spoil the presentation.
Speakers are nasty boxes. They are designed to throw sound around. When you put them in a room, they will interact with it.
Lower frequencies will start bouncing off walls, higher frequencies will start sounding dismembered from the rest of the set, etc.
Room EQ helps mitigate these unwanted artifacts to a certain extent. Room treatment with EQ is a better option, but treatment may not be practical sometimes. A fair amount of effort goes into finding the correct placement in your listening space.
Where does the amp (IA or AVR or separates) come into the picture?
Well ... firstly they are the ones that are powering the speakers to do their thing.
Most entry level IAs or AVRs will struggle to drive some speakers plainly because they don't have the power to do so.
Let's assume a set of speakers need 20-30W to come alive. The amp behind it should at least be able to deliver 50-60W of clean power.
Clean power means no distortion in sound.
Eg.
You may find the drums or mridangam not up to the sound level/preference with an amp-speaker pairing.
Natural tendency is to increase volume. If the amp is not able to hold its ground, you will hear distortion.
It'll be loud, but distorted. When this happens the overall presentation suffers.
Here is where the specs of an amp come into play. All components are designed to a price point.
In AVRs with a whole lot of stuff packed in, the amp and power supply section is usually smaller in capacity.
It will work well for HT in most cases, but sometimes for music presentation it may be found wanting.
Does this mean IAs or separates will always outperform them? No. Every amp (+power supply) has this about them.
If an amp's power supply can't hold the voltage level presented to the speaker, distortion happens (may be even clipping).
So if you don't listen to your music too loud or you are in a near field setup (less than 6 feet from speakers) in a small room, an AVR might work well enough. It will do multiple audio format decoding too and video stuff, with EQ/room correction and have the ability to host one or more subs. It would be a great one box solution, if your expectations are met. If not, maybe an IA or separates would be worth exploring.
This is why most of us on the forum say, please audition and be convinced.
Also, what works for you may not work for me and vice versa. Eg. I have a 50Wpc AVR (in 2-ch mode) and dedicated stereo amps ranging from 50-200Wpc. The most enjoyable music presentation I get in my room for my ears is with a 55W stereo out board amp coupled with a tube preamp. Would I suggest you to go this route? No. Would I pack these up and play just from AVR (50Wpc). No, again.
I didn't like what the AVR does in my home for music listening. Movies, it is good enough and does its thing. Music, it didn't meet my expectations.
Hope this ramble helps clear some things
Remember, there is no right or wrong way to enjoy music. Just your own way.
Cheers,
Raghu