The praise around the K13 comes from how convincingly it delivers that R2R-style warmth and musical flow at a very approachable price, plus the fact that it’s a feature-packed unit. For the money it’s easy to see why people get excited about it, hence why I purchased one. The Chord Qutest, on the other hand, plays in a different space it’s cleaner, and leans neutral. They don’t get compared all that often because, realistically, they’re built for different expectations and budgets.
If you’re already in Qutest territory budget-wise but are curious about what a proper R2R implementation can do, I’d steer you toward something like the LAiV Crescendo Verse, especially if you’ve got headphones capable of scaling with it. If your focus is strictly a DAC and you want that classic R2R character done right, the Denafrips Ares 15th Anniversary Edition is a more purist choice.
But if your ceiling is £500 and you just want to enjoy music without overthinking it, the FiiO K13 R2R DAC is an easy recommendation, it gives you a taste of that richer, more “analog” presentation without the financial commitment. It's a great Dac and is easy on the eyes.