best rca cable for deep controlled bass

PURIST great everything.

One of the best interconnects I have found for deep, tight, controlled bass is XLO signature. Back in the day they were highly rated by Stereophile and TAS, Then it was the "Signature 1.1" The current version is 3.1. They are unshielded, but most of the time that is not an issue. The Kimber Hero is also good for bass, but not in the same league as the XLO, but it depends on what you want to spend.
Here is an audiogon thread on the 1.1
http://forum.audiogon.com/cgi-bin/fr.pl?rcabl&1027724248
here is a review of the newer version
www.ultraaudio.com/equipment/xlo_electric_signature3.htm

With adding Furutech Evolution 2  bass  in my system dissapeared, prior to that i had some cable from Sroll - boutique company in east Europe. With Furutech I get slightly better resolution and air. So cable can sound weaker on bass then some others, simple as that. I heard Acrolink and Ansuz is good balanced cable.

Good (controlled) bass can often sound lacking from smeared (tubby) bass at first. Further improvements to your system then eventually deliver bass textures , decay and ambient cues from the recording venue.

Like others have said , look to improve your power supplies and grounding for good bass (and good everything else for that matter). Then vibration control.

Assuming you have your room / speaker positioning application correct.