Dynaudio C-1 or Harbeth-7-es-III

I would choose the Harbeth. I think they are more "musical".

As a C1 owner (never heard Harbeths) I vote for the C1. I also (on Monday) just moved from SS (Bryston B100) to Octave V70se tubes. Fantastic system synergy.

Ideally you need to listen to them both preferably in your home with your electronics.

That is a bit of unfair as the price difference between these two speakers brand new is quite big.
Having heard both speakers, I'd say both are really really good speakers & its hard to go wrong with either one.
The harbeths are more forgiving, easy to drive & can sound good to really great with modest gears.
Dyns- you will have to work harder to make them sound good as these are kinda hard to drive & quite revealing.
personally, i'm more inclined toward the harbeths esp having used them for years and they are really very natural sounding.
Best if you can hear both as in the end, its what you hear that matters the most.
The C1 are probably best compared to the SHL5s harbeths. Which again between the two, I would choose the SHL5s. The harbeths has a certain midrange naturalness that is hard to acheive from other speakers. YMMV.

I own C-1's and have owned Harbeth 7 es III and SHL-5's. I have huge respect for both Harbeth models and have enjoyed both of them, though the metal tweeter in the 7 es at times can be metallic. The midrange, however, is sublime.

As noted by Nolitan, the Harbeths are more forgiving and sound quite good with modest gear and if your objective is to kick back and
listen to music without pushing the envelop, the Harbeth's are an excellent choice. The are indeed very musical and satisfying.

The C-1's are on another level in terms of bass energy, transparency, speed and high frequency sparkle. Like most really excellent speakers, they will take work to get it right, but the rewards can be hypnotic. In a small to medium size room, they can achieve a level of realism that is truly amazing for a speaker of its modest dimensions. If you are willing to invest the time and resources, they are among the elite monitors available.

With post such as this one it depends on the type of sound one is looking for..

As pointed out by Logenn, C1's for transparency, speed and high frequency extension. The Harbeth for midrange. In other words the C1's offer a cleaner kind of presentation while the C7's more organic. I'm not too sure about bass energy of the C1's being superior to the C7's though as as both of them are fairly close in the frequency spectrum reaching down to 46Hz and 44Hz respectively. I would think it's the bass character that differentiates between the two --the bass of the C1's being cleaner, taut and punchier while the C7's more rounded and diffused owing much to the "lossy" cabinet design.

One advantage of the Harbeth is one doesn't need to spend too much on electronics in getting the best out of them(flea-powered amps work fine due to the easy load) while the Dynaudios are a lot fussier and require some serious quality kit and quite a bit of current behind them to sing to their potential. Otherwise they would sound like crap.

Both are excellent speakers.