Do I need upgraded power cables?

You ask good questions. Your system seems pretty well balanced.

Looking over your system. I think the biggest bang for your buck would be a good quality power conditioner... I recommend Shunyata or Isotec. It has the advantage of improving much of your system. If you plan on upgrading your system, then getting a good one will provide benefits far into the future. Since modest audio components basically scrimp on power conditioning in the component, external power conditioning can do a lot. Audiophile products like CDs, DAC, preamps tend to weight 30 + pounds... mostly from internal power conversion and conditioning... so that is one of the aspects not fully addressed in modest equipment.

Your integrated should be plugged directly into the wall. All power conditioners limit the amp. So, you are likely to get a notable improvement with a good quality power cord.

If long term you want a much better system, then the question of when to stop doing little tweaks and upgrade components. You don’t want to put too much into cords and wires when you could upgrade a component.

Having said that, if you want to upgrade your system sooner vs later... I would recommend a power conditioner now... then stop and save up for... a better preamp... which you would plug into the power conditioner and only use the amp portion of your integrated. Then as money permits upgrade other components.

If you simply want to get the very best performance out of what you have, then power conditioner and power cords. I found inexpensive ~<$200-300 are not generally worth it. Try used... used cables dot com. The integrated will get a pretty good boost from a good high amp cord. sThe rest of your equipment... not sure. You may have to try it to find out. 

So great questions! I will start by saying “everything makes a difference or nothing makes a difference.”

The question for you is, it worth the money in the end? Again, already stated above, you will have to decide and make sure you have a return option.

So for me in my system the upgrade from the very same Panamax to a Audioquest Niagra 1200 was not subtle! you are correct the Panamax is basically surge protection, no noise filtering or suppression.  After that I proceeded to change out the power cable  to the Niagra, then to the amp. The next would be your digital power and or pre amp. A great way to do this is using the lending library at The Cable Company!  Call Steve, tell him what you have and pay to loan them out for two weeks. If you can’t tell any difference, return them and you had a nice forced listening session, if you did hear a difference you buy new or demo and apply your loan fee toward the purchase. A win win for very little money.

I will leave you with this, sea salt tastes different than mineral salt, and pink salt tastes different still!  They are all salt!

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.