Would my system benefit from cable upgrades?

op

i am with @mesch - don’t spend too much on cables, improve your room, your components

your speaker cables and power cable are just fine, totally in line with the quality of your system... as @soix says, if you play with cables to see if you hear a positive change, try a nicer set of interconnects - buy used, under a $150 a pair, read up on the sonic traits of various brands, and adjust according to where sonically you want to take your system (more open treble? smooth out sibilance? more body to voices? and so on...)

as for @ted_denney saying "A better question, what system would not benefit from cable upgrades?"

my answer would be, a relatively nice sounding budget system with quality bottlenecks in room matching and one or more components in the chain - not to say cables wouldn’t benefit, but it is a matter of priority of what to improve first, for greatest sonic benefit

To answer your question yes the cables will make a difference. But a better path would be to sell the motion 40 then add your $2k-$3k to buy a better pair of speakers. Shop the used market.
 

if you’re really itching to upgrade cables you can try and replace your generic interconnects with something like the BlueJeans or the Mogami Gold with whatever is left of your budget. Just my take on it. 
 

Once again: 

     NO ONE can tell you whether/how your system, room and/or ears will respond to new/improved interconnects.   There are simply too many variables.

     The only way you’ll know for certain, is try them for yourself.

     The least expensive way: contact the guys at The Cable Company and take advantage of their lending library.

     For a pittance, you can try a few of their offerings and the rental fees are applied to any purchase made.

     In you shoes: I’d try the three Audience Ohno cables, currently available (RCAs/url below), between your TT, DAC, SACD player and Vincent.   With new/improved cables, in those critical positions: you should easily gain the knowledge you seek, one way or the other.    Even with your current speakers.

                   Whether to explore/spend further: up to you!

                    https://www.usedcable.com/audience_.html

                    https://www.thecableco.com/lending-library

Read this first. Then decide.

I think quality cables that are reasonably priced are the route to go.

As others have stated your room is a huge factor. You will net better results than spending $$$$$ on copper and silver and...

@mesch and @jjss49 are right.

More insight.