Speaker cable suggestion

You are welcome.

There are other smaller sites too, like Audio Circle, AudioAficionado, Hydrogenaudio that have for sale items too. I've never sold there, and some, like AudioAficionado, require you to be a member (pay a fee) to visit the members for sale section. There's always Craigslist too. I've heard of fellows who got lucky there, but I've never found anything. Happy hunting.

The Master Built (By Delphi Aerospace) Purple Line are superb. Highly recommend these speaker cables. Not well known currently but outperform some of the mega-buck speaker cables I have owned.

What about Frey? It seems, for a little over $1k, I should be able to get a pair. I'd think the synergy with the Heimdall ICs should be good. How would Frey stack up against Stealth Hybrid MLT, AZ SS, etc?
I currently have one of the sc mentioned above pairing with the Heimdalls and am trying to be very careful with system matching. I'm not one for trying out a lot of cables.

Well if you are looking for neutral and transparent, the Nordost cables are about as far as you can go in that direction, so you should enjoy them.
I think the Stealth Hybrid MLT are one of the best buys in cables at their used prices. Almost as fast and transparent as the Nordost, but with a slight hint of sweetness.
The AZ SS are more full bodied and natural sounding, a different type of sound all together. I would not call the AZ sound neutral or transparent. So it all depends in what you are looking for.

One word of warning: I have found that, like most cable companies, Nordost sound can be cumulative. I have often enjoyed a little Nordost in my system, however, I've twice tried going all Nordost and neither time did I like the final sound. Instead of fast and exciting, articulate sound, I started noticing the lack of musical weight and listening fatigue started to become a bigger issue. As always, YMMV.

Hi Jmcgrogan2, thank you for the info. It's very useful. At the moment, I would say my system has quite good musical weight (esp. after I "somewhat" addressed my power distribution with PS Audio products - dectet, power port premier receptacle and ac-12 power cord). My ICs are Heimdalls (both XLR and RCA) and my speaker cables are one of sc mentioned above (I will leave out the name). My speakers are Focal Electra 1028Be and amps are all Pass. I feel I have open, smooth and "meaty" (for lack of a better word) sound. The area I'd like to improve is the mid-bass naturalness and speed.
The reason I know it's the speaker cables is because I also have cheapo Tributaries 12 gauge sc. Switching this in and out with the current sc, the mid-bass problem is gone (speed is still the same) despite all the other shortcomings with the Tributaries.