Speakers with the most detailed midrange? (non-ESL/planar)

@woofer72

I use ATC EL150A with their P6 amplifier and new ATC built tweeter. I also have the C6 subwoofer which I don’t use for 2 channel stereo (not needed even in a large room).

The new ATC tweeter is worth having. Having owned for years the SCM 20, 100 and C6CA, I highly recommend the 150. All ATC are superbly balanced but the 150 is IMHO their best. The ATC 15 inch woofer is just superb. Not many think about woofer quality with ATC because of their mid range but IMHO they have the best 15 inch woofer on the market. ATC actually got started with Supertramp, AC/DC and other stadium rock bands of the late 70’s - based purely on the quality of their woofers that were used in arrays of bass bins. The woofers in their hi-fi and pro studio speakers are massive short voice coils in a long gap - ultra linear response. A big part of mid range clarity is down to the woofer performance - don’t under estimate this factor!

Klipsch Heresy IIIs somehow get midrange right with their 1.75" titanium diaphragm driven horn. I was surprised by this as I'd never previously owned a horn speaker for my hifi rig needs, but there it is. These things are relatively inexpensive for a USA made item, and in my ever humble opinion are way underrated world class speakers. I use these with 2 REL subs that do a great job of fooling me into thinking I'm having more fun.

@gosta -
The Kii Three wouldn't have the SLP capability I'm looking for unfortunately. From what I've read about the Dutch & Dutch they are a bit shy of the ATCs in mid detail. The big attraction about them is their ability to adjust to rooms. Cardioid bass etc. I know you can't go on what you read but I find its a good starting point to reduce the amount of speakers one has to audition. I would still like to hear both of these.

You make an interesting point on the Unity Audio Boulders. I think perhaps the room I heard them in was not treated well as the bass was a bit too much and the mids were very obscured. I was very disappointed. That mid/tweeter coaxial driver is certainly interesting. Elac uses it in some of their higher end speakers. I've never heard those.

If you ever do A/B compare the Lipinski to the ATC, please let me know what you think. I would be very curious of the outcome! Since the Lipinski is based on the Dunlavy/Duntech design, it really is a world class speaker. Do you have the yellow cones or the newer upgraded black cones? The newer versions have thicker and larger cabinets for better bass. They also claim a smoother midrange, but I'm not sure how they achieve that. Perhaps an upgraded capacitor in the crossover. I think a pair of Lipinski with a sub or two would be fantastic. In a two way design, I'd be concerned about the distortion on the mid frequencies at higher volumes. 

Regarding smaller speakers in conjunction with subwoofers, I'd be curious to hear the Magico Q1 as well as the newer Paradigm Persona B with the beryllium drivers (!). Personally I refuse to pay the money Magico is asking for the Q1 for bookshelf speakers but I would be curious to hear them and see how detailed they are compared to ATC. The Paradigms seem very interesting, unfortunately they are ported bass reflex designs. I can't deal with unfocused bass. One trick I have found useful to bypass the bass reflex design is to crossover to the subwoofer at a higher frequency than the frequency the port is tuned to. I did this with my Dynaudio Air20s and the bass tightened up drastically.

@gosta 

You may also want to check out Accuton driver based speakers. Salk uses them. I've heard fantastic things about them. Supposedly the newer drivers aren't as fragile as the older designs. There is also a driver from Raven that looks interesting. I believe Nola uses them:
http://ravendesignstudio.com/line-source/
I'm just a bit wary of getting too much into obscure drivers and speakers. 

I'm also curious to hear the ESS speakers with the Heil AMT.

Thanks for your detailed response and information!

@shadorne 

I have read that the new ATC tweeter is a great upgrade. I can certainly see that, as the only real shortcoming I found in my SCM100's were the high frequencies displayed sibilance and they lacked air (rather boxy sounding). This caused a bit of a dead sound. I'm really curious to hear the upgrade.