You wouldn't say that these connectors are night and day soundwise, just by looking at them. They look quite a bit alike, although the Furutechs are a little better finished. The plastic housing is a little smoother and so is are the conductors which are nicely polished and more shiny than those of the Hifi Tuning. But as it turns out yet again: looks aren't everything. Although... there is an analogy going on between the Furutech's appearance and their sound... read on!
To compare them, I installed them into a CP-audio Ultimate Clarity extensionblock and ensured that I used the same length of cables inside.
Furutech FI-E30 Rhodium
This connector certainly looks the business but soundwise I found it to be disappointing. It sounded a nicely detailed, but a little slow, and dynamically compressed. Even without comparing to the other connectores these characteristics stand out. This connector simply sounds uninspiring. Neutral but somehow synthetic. Compared to its golden brother, it is dry, thin and has poor communication skills. Rhodium or no, it doesn't have good PRAT.
Furutech FI-E30 Gold
The gold plated connector sounds better than its rhodium counterpart in that it is more involving, has more color and warmth and richness and has a little more speed. Although it sounds dynamic at first, with time you start to notice how everything still sounds a little too smooth and too compressed, compared to regular outlets. The Furutech however, is much more refined, fluid and detailed than regular outlets.
Hifi-Tuning Schuko outlet
While both Furutech connectors manage a little bit more air at the extreme HF and are even smoother, the Hifi-Tuning simply sounds more real. It is at once more acoustic, more dynamic, more engaging, fuller and richer and not at all dry, synthetic or sterile. This would be my pick of the bunch.
For me, the Hifi Tuning outlets were the best. Alas, by the time I had finally written this review, the HT outlets are no longer available. In the Netherlands and Germany at least. Apparently there wasn't enough demand. That sort of makes this review more or less pointless... but at least it serves the purpose of pointing out that there are indeed quite large audible differences between schuko outlets. And the most expensive one doens't neccesarily sound best. What's more: depending on your system and taste, you may even prefer standard outlets over the more refined highend ones.
Additional note dec 2011:
Furutech as a brand seems to have a certain house sound, throughout its cable and connector range which is a smoothness and lack of agression. Also, emotionally, I find that Furutech is always appealing. Technically though, speaking only for the connectors, the brand can lack attack and drive, when compared to standard connectors and IeGO. So, whether or not this will be the brand for you depends on taste and system synergy.