Speaker cables for Simaudio/ Dynaudio

I have narrowed down my search for speaker cables to two: Synergistic Research Tesla Accelerator and Nordost Heimdall. I have a Simaudio I-7 integrated and Dynaudio Confidence C1 speakers. I am currently using Signal Cable Ultra Speaker Cables which I have had for a few years. After various upgrades to speakers and electronics, speaker cables are my last upgrade.
Any thoughts on these two choices?
I used Synergistic's Resolution Reference FX's for years with Dyn Contour 5.4's, a great combination, I'm still using them with my One-Off Tannoy custom HPD 315's w/custom crossovers. Tried the Teslas, but thought the improvement not worth the difference in price. I am using the Tesla Analogue Vortex, though, in a 3 meter run from table to preamp, (phono pre modded Simaudio LP 5.3, Sonic Euphoria passive line stage preamp. Great symbiosis in all regards with this combination of equipment.

Synergistic and Dynaudio+Simaudio, thumbs up!
My vote goes for the Nordost Heimdall. I too have the C1s but powered by a Bryston B100. When I demoed speaker cables I had to 'squint' to hear the difference between the Heimdall and Frey (although I did end up buying the Freys). I never auditioned the SR line so I can't comment on them. Very happy with the Freys. Great synergy.
I use the Heimdall speaker cables and interconnects in my system (Thiel 2.4 speakers with ARC amplification and source) and I think they are the sweet spot in the Nordost line in terms of price/performance. Having said that, it does not mean they will be synergistic in your system. If your local dealer does not carry both lines or won't lend you the cables for home audition, i suggest calling The Cable Company (http://www.thecableco.com) and have them send you a set of each. Only way to tell which will work better in your system is if you try them out. Good luck.
I think it would help to know what you don't like about the sound now, and what you're ideally looking for. Granted, a cable may not fix or change everything/anything, but it helps to know your tastes.
I am looking for a tighter control of the bass and a greater clarity in the midrange and highs; an overall increase in transparency.
I would imagine it's very rare that someone has heard both of these cables with your amp/speaker combination, so in general the best anyone can do is venture an educated guess, which is going to be very general, since we also don't know what else is in the chain (front end and IC's). I have had the Nordost in my system and while they definitely provided increased clarity across all frequencies, and were very tight/fast cables, I ultimately found them a little on the analytical side of neutral. All the details sparkled, but a little too much. I was using them with a Dali Euphonia's, which have a ribbon tweeter, and the Pass INT-150 which in my opinion is close to your i-7, which I have also heard. The esotar tweeter in your Dyn's is remarkable, so this may not be a problem for you.

A buddy used the Teslas with his Dynaudio Contour 5.4s and thought they were excellent. This confirms my own experience of Synergistic Research, which I feel are very neutral cables. If I had to compare the two, I feel that the Nordosts focus you in on the minute details while the Syns make a more holistic presentation. Don't get me wrong, they're both excellent at detail retrieval, but in my experience I've found the Heimdalls to be a little more analytical. FWIW.
My source is a Simaudio Supernova cd. I am using a Nordost Heimdall xlr interconnect.
Well, one could assume you're already familir with the Heimdall in your system then. I would just bite the bullet and get the Heimdall from Cable Co or something, that way you can return it if you don't love it.
I think I am going to have The Cable Co send me a pair of both the SR Tesla Accelerator and the Nordost Heimdall and compare.