Sense you have them side by side... What's the pros and cons of each?
Of the 5LEs vs 6s?
Based on my most recent listening session with the two - which was on the Cinuas Converter -> Chord QuteHD -> EF-6 - I could say the following:
- The only pros of the 5LEs - vs. the 6s, not in absolute term of course - would be the darker tonality, which make it more like a in-studio sound vs a live sound. That and... the weight. That's it, really, the 6s is better in every other ways (technically).
- The 6s have fuller mids - which is readily apparent and not really expected because at the same time they are less warm/more linear; there's no mistaking here, switching to the 6s brings a lot more meat on the bones (technical), but less warmth (voicing).
The extension is better in both the treble (oh so smooth and well defined! I could use a bit less elevation but my somewhat warm source and the pleather pads can deal with that) and the bass. The sound is smoother throughout the whole audio band and the level of refinement is better all around. I always said the 5LEs are a bit "raw" in the treble (which doesn't bother me, it's even quite good for fast paced rock), here it's certainly not the case. The scale is bigger (wider, deeper and also taller) and the dynamics are better too. Note that this last point is quite new to me; you probably remember that I complained about the lack of dynamics with the 6s on the SA-31. This is no longer the case on the EF-6. Finally, the level of details is another league entirely.
The cons of the 6s would be the elevated treble that can be too much on poorly mastered rock tracks (or poor compression) and the linear voicing that might be too "polite" or "boring" for some people. While I certainly love some bloom and warmth in the sound (e.g. HE-500) I can never find the 6s polite in their presentation; not with that level of slam and dynamics! They are the fastest headphones I ever listened to, period.