So...I spent more than five months listening to RCA interconnect cables... My near-field setup is a pair of Omega Compact Alnicos (94.5 dB @ ohms) driven by a Chord DAVE. As far as I know, the Chord DAVE is the only preamp + DAC with an output impedance low enough to drive speakers directly (0.0055 ohms). Typically that's the whole purpose of having a discrete amplifier. The Chord DAVE's RCA output is capable of providing 2 watts of power at 8 ohms with 0.5A of max amperage. The single-ended RCA outputs provide 10 times more current than the XLR outputs, hence the choice of RCA. This has made it an attractive choice for use with high-efficiency speakers such as those from Omega, Voxativ, Zu Audio, AER, and friends. After I get home from every show, I listen to this unassuming system and I'm blown away by the level of focus, detail, quietness, and transparency this direct-to-speaker arrangement provides. It's bold of me to say, but in comparison, more than 95% of the setups at these shows sound veiled in one way or another. I wish I were exaggerating. Now the DAVE isn't the warmest of DACs so tone control options are limited with a setup like this. There's no discrete preamp, additional ICs, fuses, amplifiers, or speaker cables to adjust tone. Needless to say, the RCA cables are considered a primary component of this system. The Omega CAMs are known for their sweeter signature which complements the DAVE very well but, as we know by now, different cables interact with different speakers and amps which results in huge sonic characteristics. Unlike speaker cables, whose inductance and impedance is of utmost importance, the weaker line level signal of ICs are less impervious to external noise (EMI/RFI) so low capacitance will be a primary design goal. Since I'm using the interconnect as a speaker cable, I technically need all values as close to zero as possible, assuming I enjoy the sound. http://www.neotechcable.com/product2_3.php The following comments are mostly generalizations so don't take them as gospel. Design approaches

Length - equal in length to prevent phase shift
Combination of stranded and solid core wires - Flexibility
Low contact resistance - The RCA connectors should be able to withstand a high number of insertions.
Varies ways of twisting and wrapping conductors
Combination of different metallurgy for both signal and ground conductors
Directionality: Due to the mechanisms used to draw copper through a series of diamond dies, the crystalline structure runs in a specific direction. Some companies have found ways around this (e.g., Harmonic Tech, Acoustic Zen). The directionality should primarily affect the higher frequencies.
Metallurgy
Copper - warmer with more body
OFC
6N UPOCC
Silver - focus, fast, detailed, uptilted sound, expensive. Minimum of 3N.
Soft annealed silver
Gold / Silver alloy - Supposedly the best of all worlds
Silver-plated copper - Corrosion resistance
Graphene
Palladium
Geometry
Coaxial solid / Coaxial stranded
Twisted pair / Litz - Many ways of implementing this
Braided
Spaced-away
Flat / Sandwiched
Impedance, resistance, and capacitance measurements
Cryogenically treated - From my listening, this seems to accentuate the highs and provide better resolution at the cost of, you guessed it, body and warmth, especially in the mids. This treatment supposedly "squeezes" the metal which forces out any embedded atmospheric gases.
Shielded or unshielded - Unshielded is usually preferred.
Tinned copper braid sleeving spaced away
spiral shield - easier to work with
foil-wrapped
Solder, solderless, or crimping?
Gauge
24 gauge seems to be the ideal size for ICs
Solder

cardas quad solder

Copper based solder sold by Chimera labs is very good but must be sealed with clean teflon nail polish to prevent corrosion.

Wonder Ultraclear

mundor

chimera

johnson

Dielectric/insulation material - lower dielectric constant is more suspcetible to outside interference
Air - Dielectric 1
Kapton
PTFE/FEP (Generic Teflon) - 2.0
XPLE
Foamed Teflon
Polyethylene PE
Foamed Polyethylene - supposedly really good
Cotton -1.3
Balsa wood
Oil
PVC - Mostly as jacket material
Plugs
Keith Louis Eichmann's Bullet plug
KLEI Harmony RCA plug
Furutech
Oyaide
WBT

- wire gauge

- solid core/stranded conductors

- geometry (coaxial, two conductor with shield, star-quad, ...)

- type of dielectric (Teflon, foamed Teflon, polyethylene, polypropylene, ..)

- types of shielding (aluminum mylar, copper foil, bare copper, silver-plated copper, ..)

- outer jacket material (PVC, Teflon, synthetic rubber, ..)

- writing/logo to print on the jacket

- (optional) outer polyester sleeving

Of course a lot of these design choices are part of the manufactuer's "secret sauce." I've done one-on-one comparisons but even compared 12 interconnects at the same time, back-to-back, all while writing down notes in a spreadsheet. I'll rinse and repeat every couple of days to ensure my findings were consistent and did even listen again after a few weeks.

BJC	commodity Belden and Canare OFC copper.
KabelDirekt Pro series
High Fidelity Cables Reveal	vs. CT-1E More forward and meatier sounding than the CT-1E. Edges are a little fuzzier but I feel the overall tone is more natural. This cable might even be more dynamic, especially for the climactic portions of music and I've found myself preferring this cable the more I listen. vs. Danacable Sapphire Doesn't have the resolution of the Sapphire vs. Audience The Reveal is more "narrow" sounding vs. UIT UIT has smoother mids but the the Reveal is meatier. A very balanced sounding cable Transparent and involving sound. Rawness Better than the cheaper PAD and Cardas...and most of the other cables Musical, clean, crystal clear, and precise articulation. There are a tightness and refinement in the sound. Similar to UIT and Audience. Not just good for the price, but too good for the price. A little bit of grain in the treble region, I'm just nitpicking now. Very musical and engaging overall. Highly recommended, especially for systems with a warmer tilt. much more open than the PAD and cardas but lacking in the timbre/tone department. a little uplifted but extremely detailed and resolving. Crisp Untroubled by the complexity of rhythms Fresher dynamics vocals hover cleanly and clearly over other elements
High Fidelity Cables CT-1 Enhanced	A very musical, euphoric, and rich sounding cable. It maintains coherence and acoustic control, even with heavy metal. Never falters. Timbre and tone come off very natural. Background isn't super black Treble doesn't have a lot of shine The Danacable Sapphire has more resolution but much less body versus the CT-1E. The Danacable is quieter, has a smoother treble, and has more depth. However, I found the HFC CT-1E's timbre and tone to be more aligned with my tastes. It's an intimate sounding cable Overly warm, masks the details A little drier on the top end Fusing of instruments
Danacable Sapphire RCA	Great tone, timbre, not as airy and real as the Audience but sounds really good. A bit flatter than audience not as dynamic. wow, i think it's been breaking in on the sub and it sounds great. Great warm sound, layering is ok though.
Danacable Sapphire Reference RCA	Grandeur
Vovox Textura RCA	I spent a lot of time with this cable. The only thing it lacks is probably soundstage and depth. It's very engaging, perfect amount of density, and great resolution. Textural cues are present and provide for a very euphoric listening experience. Timbre and tone is probably the most accurate out of the bunch and only falls short with the resolution to make it truly "real." A sweet sounding cable. vs. Audience Vovox is more weighty and meaty Vovox is less detailed in every way and doesn't have anything close to the Audience's layering capabilities Not as well delineated or airy as the Audience
Vovox Fortis	there's a softness, guitar transients aren't as apparent. but there's also a realsim to the midrange. this might be the perfect balance between soundstage, detail, and warmth. micro-dynamics are missing. missing a little delineation in the shine but so melodic, I've never heard a sound this sweet and smooth. Plucking of guitars have a softness. Definitely less holographic, misses a bit of the texture on the instruments. the music doesn't breathe as much as I want it to. There's something really special about this cable...it is probably the most honest cable out there. Sweet & honest. Doesn't have that expanded air. There's still a softness to the edges but tonally it sounds great. doesn't feel like it breathes fully vs the Audience but has more warmth. Not as much depth as the Audience. A bit flat sounding, not holographic. Energetic edge is missing, the softness make it sound less refined overall. I like everything else though. smooth and analog but I feel it's not allowed to shine. Sinewy organic textures Muscular Remarkable instrumental timbres and detail Vibrant tones
Furutech Lineflux	Warm-ish tonality without being overdone, trading off resolution and air. Slower transients than most of the cables in this lineup. Doesn't have the contouring of the Vovox Textura or even the HFC Reveal That lack of resolution misses out on some important micro-details that provide cues to emotional aspect of the music. Great timbre and tone but misses out on that dynamic tacility. Not enough layering and separation to be engaging. doesn't have the roundness with vocals, kinda smeared but a rich midrange. not very quick or detailed, especially with transients. Lacks dynamics and air, not worth the money. Super flat, not texture, lacks roundness, brighter than teh vovox shallow Velvety mids
Zenwave D4 Ultra	Fantastic sounding cable and a really good one to pair with speakers. Very spacious, holographic, fun, and resolving. You hear every part of the song without losing musicality. For sometracks it did get a bit bright but overall i like it more than the furutech lineflux. not many complaints, just a bit lean for my tastes. Needs 2 thin layers of meat and it would be perfect. Doesn't have enough midrange density and low end rumble for me. Fantastic soundstage, tightness all around, really no big complaints besides wanting a meatier sound. some grain on vocals (male and female). Brass just doesn't have the density to be real. Not enough meat for me but really dam good resolution, top 4 probably. timbre is a bit off and pianos sounds too light. Not bad sounding at all. Closest to the audience, very good control, very quiet, very spacious, detailed, smooth. great imaging, only drawback is a lack of meat which the HFC Reveal has more of. Not much to complain about. vs the audience, it sounds a few notches brighter while the audience has more roundness and realism overall. the audience is the cable to beat.
Purist Audio Venustas	Really nothing to complain heavily about. There's a constant layer of grey in the background to help smooth over the music but it's a good thing as everything works well. Great bass, soundstage, musicality. The only drawback is that because it's so silky, the instruments and vocals don't sound like they float in the air but rather blend in a cohesive and musical way. It's really PAD's signature and those who love it will love it. I really like listening to PAD as it's just an easy and smooth listening. Still tons of detail, not a lot of treble definition though. never gets abrasive at all. Definitely not a "exciting' or "fun" cable just enjoyable. Flat compared to the museasu, not as well delineated either or refined, timebre and tone a bit more lighter than natural, smaller instruments, bloatier sound but still smooth and musical. lacks the focus of the museaus (and other cables). flatness is a problem.
Audience AU24 SX	Amazingly palpable sound. Maintains composure. Fatty bass. Perfect cable. Tacility, body, fast, lush, musical. so MUCH texture...competes well with texura....wonderin wondering. guitar plucks have so much dimension and life. It has all the best things...difficult to find flaws. Very well layered, dimensional, quiet...seems impossible. I've been startled quite a few times by the dynamic contrast I heard from a few recordings. There's a lot of depth, weight, mass, and intention, I really love this cable. The only thing is, the speakers don't disappear. Even within the mids, it's never crowded and the instruments never interfere with the vocals...this is a beast of a cable. a very detaile sound, perhaps doesn't have the tone/timbre of the lineflux but sounds better. very well controlled but needs meat. Very smooth, yet detailed, natural, and real. Has more sonic dust over the UIT, more warmth and realism. Not as clean but melodic. More natural and tone vs the UIT. sounds like real instruments. Bass plucks and piano have proper weight. Incredible dynamics. Much better focus than the CT1-E and UIT. A very tactile cable, great texture and dynamics. Not as well delineated and crisp as the UIT. great tone and timbre though. bass is super tight. Id' be pretty happy with this cable. Not as refined as the UIT (edges). breathes the most freely out of all the cables. a little glassy with streams. by far the most realistic sounding cable with the most gradations in sonic spectrum. very visceral, lush, and palpable. just lacks a tiny bit of warmth. at high volumes on DAVE it gets a little harsh. much bigger soundstage, resolution, less veiled, more vivid and airy than the vovox textura. textura sounds a bit veild and flat in comparison, doesn't breathe as well as the audience, a little restrained. Human cues Reolving powers Digs into the recording and throws a wider soundstage Emanates from a point in space not as a diffused image Hear further into the mix High-frequency clarity and definition Piano: Impact of hammer on string, shifting of the dampers Large and small-scale shifts Moreover, you hear the oboe's timbre coming from the oboe's position, the violin's timbre coming from the violin's position, and the hall reverberation surrounding the instruments. Pitch definition and articulation Quick or fast reproduce the suddenness of transient signals. Tight time domain controlWhat's amazing is that I was looking for something much denser sounding but the staggering insight this cable provides The best products will reveal all the low-level cues that make music interesting and riveting, but not in a way that results in listening fatigue
Zenwave D2 Interconnect	bass has a bit over overhang vs the rest, esp versus the audience. great timbre and tone. just flat and lacks tacility and texture. also poor layering, mids get crowded. not a lot of shine a but fuzzy around the edges. The best thing about this cable is that it sounds natural and it's accurate and warm but just too flat with a bloaty mid-bass that blankets the spectrum a bit. It's enjoyable but not hi-fi. bloaty bass, flat, no decay whatsoever. lacks shine and definition. warm but isn't fuzzy or vield just instruments aren't as convincing or dynamics. not as meaty. low resolution and clarity.
Cardas Cygnus Clear	Kinda the same philosphy as PAD, smooth the edges out and make it more analog. I have to say, the vocals have a realism to them due to the smoothness. Everything else, I find I want some of the grittiness and edge on strings etc. Brass doesn't sound like it has enough weight either. I don't think real music was meant to be heard with this level of liquid. I think liquid is the best description for these cables. no edges on vocals or instruments. there's no definition. Human voices have more grain more nuance and detail. this is akin to anti-aliasing in video or in images. smooths over the strings, not quite a natural tone or timbre, a little leaner and more polite. not enough weight or brass dynamics. overally smooth. Somewhat earthy and greyed out tonality
Purist Audio Design Museaus	I like the PAD more than the cardas at this price point. they both have a soft character but I don't like how the cardas over-smooths the vocals. The PAD maintains some of that gritiness and texture. Still some shine whereas the Cardas seems to alias the original signal a little too much. PAD is musical and fluid. Cardas is liquid and slippery. Fantastic musicality and dynamics. The only compalint i have is the lack of grit and grime. Sometimes I wonder if this is how music is supposed to sound, very fluid and analog. Tone and timbre are great, one of the best, smoothness doesn't really come off artificial either. hard to complain, but those who want more refinement in the grain and grandularity, would prefer the audience. Creamy typically a tradeoff between resolution of detail and smoothness but the Museaus does well here
UTI	forward, lots of detail, not bright. very balance. very clean, tight, and delineated, esp vs the CT-1E. guitar plucks are clear. quieter than the CT-1E as well. Very spacious, speaker disappears effect. More minor blue, it has a leaner sound, not bright. very detailed and fantastic layering and holographic sound. doens't come off analytica at all just want a bit more meat. Dyanmics when the trumpets come in isn't as impressive, doesn't go high to low or low to high in realistic fashion. it's detailed but not compared to the audience, seems to masks some low level stuff that's important. not as great focus or delineation or layering as the audience. not a bad sound, very clear and open, just doesn't sound sharp and crisp, and instruments sounds a little smaller, esp vs the audience. just a very clean and pristine sound. I think it's only in comparison to the audience that i'm not impressed but it does sound good.

Conclusion

This is what I've realized from the cables I've tested:

Not necessarily true but the larger gauge and stiffer the cable, the warmer it'll sound at the expense of resolution.
The thinner the cable the better. Just make sure it could handle the maximum current you'll be running through it. DAVE's max output of 0.5A makes even 30awg wire suitable.
Solid-core, individually insulated
Air dielectric deepens the soundstage. Maybe a corroded oxidied cable still sounds better than PTFE.

Driving Hugo 2 Upgrading the connectors on the DAVE. audible difference no design approaches at whatever cost guarantees good sound sum is better than individual parts synergistic factors I'll add more cables to this list at a later time some of what sonioc craft said This wasn't the case for digital cables, which are more arduous to design IMO.

through many whiskey blind test, I could probably correctly identify the difference between

most are priced according to sound, it corrleated the sound.

vovox + audience would've been perfect