That’s a very familiar set of observations with the Ref 5SE, and I think you’re describing a real interaction rather than a simple “bright vs warm” cable issue.
The Ref 5SE has a lot of energy in the upper mids and presence region, especially compared to the LS-16, and that can make cables that emphasize leading edge speed or extreme HF openness sound a bit spotlighted on vocals and mic artifacts. WyWire Diamond and Valhalla both lean toward that highly resolved, fast presentation, which can be impressive but not always forgiving in this circuit.
In my experience with ARC line stages, cables that slightly relax the very top octave without softening midband texture tend to work best. When a cable sounds “recessed” or “analytical” here, it’s often because it’s controlling that energy but also overdamping the harmonic envelope — which seems to be what you’re hearing with the Frey and, to a lesser extent, the Cardas.
A few things I’d consider before chasing another cable immediately:
• Give each interconnect a full week if possible. The Ref 5SE is quite sensitive to dielectric settling and connector interfaces.
• Pay attention to grounding and connector pressure — small changes there can shift perceived brightness noticeably.
• If you’re running RCA, you may find that a well-implemented XLR reduces the “mic spotlight” effect simply by improving noise rejection and balance, even if the core tonality remains similar.
Sonically, I’d be looking for something that prioritizes midrange density and harmonic continuity rather than ultimate HF extension. Not rolled off — just less forward up top. Cables described as “neutral” can still sound lean here if they’re optimized for speed over body.
You’re on the right track by listening carefully and letting the system tell you what it needs. The Ref 5SE is capable of fantastic organic clarity, but it’s definitely cable-revealing and not shy about exposing mismatches.
Curious to hear where you land after more time with the Valhalla and the others.
