I would always recommend a higher gauge cable if your amp was 20' away from your speakers, but since its only 5' you should be okay with a decent set of Monster or entry level Audioquest cables. They are quality cables that are well shielded that won't break the bank. There is a website that will allow you to try out a number of cables in your system (see below) so you can decide if you hear a difference or not. You should also check out Audiogon, which is a website for used audio gear. I bought my speakers and cable there a few years ago for a fraction of the retail price. Most high-end folks baby their equipment so you are usually getting pristine stuff from someone who is on the upgrade path.
Denon makes decent equipment, but you are asking a lot of a 55 watt amp to drive 4 ohm speakers. If you want to stay the receiver route I would recommend Anthem, I have one of their pre/pros that I bought used on Audiogon in my system and it has worked flawlessly. Marantz & NAD are also solid choices for receivers, but you should look to at least double your power and preferably triple it to 150 watts.
http://thecableco.com/content.aspx?iid=5777