speaker and interconnects, how nice do I need

I can say that as long as you buy a robustly built connector, you’ll be fine. Cables are a nasty part of this hobby with many thousands of dollars, in my opinion wasted.

balanced power from companies like Equitech or Running Springs will do more then some snake oil vodoo cable ever will.

wire world sells a very nice entry level interconnect. The key points are (1) built robustly (2) adequate shielding to prevent your cable from acting like an antenna (3) in lengths that are the absolute minimum needed.

ground noise and hum can be fixed with devices from the companies listed above. Those key points are also applicable to power and speaker lines with one exception.. Use 10 gauge speaker wire. That's good for anything you'll be using for power.

good luck

In looking at your system components I see a couple of technical factors that will work in the direction of reducing sensitivity to cable differences, compared to many other circumstances, but that have nothing to do with your system being on the "economical side," as you put it, or with its sonic quality or musical resolution.

One factor, affecting speaker cable sensitivity, is the relatively high impedance of your speakers (shown here), which is well above 8 ohms at most frequencies and above 6 ohms at all frequencies. Another factor is that both of the electronic components appear to have two-prong IEC receptacles, which isolate them from AC safety ground and therefore eliminate the sensitivity to interconnect cable differences than can result from ground loop effects, especially with unbalanced interconnections such as you require. (Ground loop effects can cause low level high frequency noise, affecting perceived detail and ambience, as well as causing low frequency hum).

Also, as alluded to in the previous comment most cable effects are proportional to length, so if you just require relatively short lengths that would also reduce sensitivity to cable differences.

A relative of mine has the same speakers as you do, and has been happy with these speaker cables from Cable Solutions, which cost a bit under $100/pair in typical lengths.

Sensitivity to interconnect cable differences is also contributed to by the output impedance of the component driving the cable. Lower output impedance = less sensitivity to cable differences, everything else being equal. Unfortunately the output impedance of your Marantz player does not appear to be specified. But given that it is a solid state component and that its output voltage is spec’d based on a relatively low load impedance of 10K its output impedance is probably reasonably low.

So all things considered I wouldn’t sweat the choice of interconnects too much, especially if you require a relatively short length. A number of good possibilities have been suggested above, in addition to which you might want to consider Blue Jeans LC-1. Regarding the mention of Mogami by a couple of the earlier posters, here is a link to a convenient source of Mogami 2534 in an unbalanced configuration. I doubt that you would be going wrong in choosing it.

Good luck. Regards,
-- Al

I would look for a "fast' slightly forward/engaging cables to help balance your system. I would look at the Signal Cable Silver Resolution line.

Whichever interconnects and speaker cables you decide on for heaven's sake make sure they're connected in the correct direction. Just like fuses they're directional, and I'm referring to unshielded cables and ICs. 

lots of good choices, enjoy the process...