Do I need upgraded power cables?

Audioquest’s thunder cable improved my sound. Use it on the integrated. Seems background more quiet, better dynamics. Idk, Maybe I’m imagining it. I also swear by cableworld’s Electra 7 on a preamp. Using audioquest’s Niagara 1200 pwr cond and Edison receptacle. A AQ z3 PC from Pwr cond to Edison, 20 amp dedicated. Do what you want, have fun.

If you are asking the question, the answer is no. 

There are times though (especially in dense musical passages) that the sound is stage is a blur - as if of all the instruments are coming from the same place.

A good power conditioner can sometimes help individual images pop by reducing noise.  Here’s an EQUI=CORE 1000 if still available you could probably get for $600 I’d think. 
https://www.usaudiomart.com/details/650092255-core-power-tech-equicore-1000/

Also, how are your speakers positioned relative to the back and side walls, how far apart, how much toe in?  Speaker positioning can also be a big factor in improving imaging and soundstage.

People knowledgeable about electricity will tell you a power cable is a power cable and won't make any difference. People that are members of the church of audiophilia will tell you the differences "aren't subtle" (a favourite). 

 Maybe my components aren't audiophile enough to justify purchasing upgraded power cords. 

You won't know until you try it. Do you buy from dealers, or used? 

If you have a relationship with a good dealer see if you can borrow a good demo ($1000+) high current capable power cord from them, put it on your amp, plug it directly into the wall and see what difference there is. 

If you hear a difference you will have to decide whether that is worth the asking price, and that will answer your question "Do I need upgraded power cables".