Cable upgrade path...

First I must be honest and admit I have never been this far with any equipment. I’m hoping for a bit of guidance from experienced individuals.
System currently consist of Oppo 203, Marantz 7012 and Monoprice Monolith 5X200 amplifier. Front channels are Tekton Impacts. Rear are PSB towers.
My speaker cables are Morrow Audio SP6. My interconnected are Morrow Audio MA2. Marantz power cord is Audience Forte F3. Monolith amplifier power cord is Shunyata Venom HC. I also use a Wireworld Matrix 2 power strip with another Audience Forte F3 connecting it to a CruseFIRST Maestro wall receptrical.
As I have pieced together this system I regularly read how others swore up and down that cables and power cords have little to no effect on a system. After experimenting I now know that is ridiculous.
The position I find myself in at the moment is I am torn as to which component to try the next power cord upgrade on next. One school of thought believes go source component out, being Oppo, Marantz, Monolith, interconnects and lastly speaker cables. Another believes start at the interconnects first.
Any suggestions/guidance derived from personal experience is appreciated.
Thank you.
When I used Transparent Audio cables, they recommended IC source to pre, then speaker cables, then IC from pre to amp. I find power cord upgrades less predictable, but also very worthwhile. If shopping used, then the order is often what comes up at a good price first...
There is no absolute correct choice.
Results will vary per one's system components, location and AC cleanliness.
Personally, I have found the best place for cable upgrades in the following order.
1) Interconnect between source and preamp.
2) power cable on Dac/CDP, preamp, lastly amp.
3) Speaker cables.
4) Interconnects between preamp and amp.

In your specific system, (not that there is anything wrong with it the way it is) the weak link might be your Morrow Audio MA2 interconnects, followed by the Audience Forte F3 power cord.

The important concept here is to make an educated guess, bust a move when you find a good opportunity and learn from your decision.
@ lak 
In regards to the Forte F3 cables. I was thinking that may have been one issue as well, so today I contacted The Cable Company to inform them I am returning them. I am replacing them with Voodoo Ultra Wave power cords. The Voodoo Ultra Wave are a discontinued model. I purchased new for well under half of original price. 

@ mental
I'm already using a dedicated 20 amp circuit. I may very well try an interconnect upgrade next. Like others, I hunt for deals because I only half *** know what I'm doing and I'm not willing to get to deep without experimenting with a company first. The other thing is, I do not understand how, with some companies, the interconnects will be as costly as speaker cables. 

@ roberjerman
I know well that not everyone is a believer, but I love it when some of you say silly things. Guys like me find you very amusing. Please feel free to keep putting yourself out there 😊
VooDoo does offer some attractive pricing on some new discontinued power cords. I picked one up for my digital end this past summer. Let us know if there is an improvement.
Curious what cable you switched out for the Voodoo and what your thoughts are afterward?