The MMDCi is the improved version of the MMDC. Better cabinet, better tweeter, better bracing, better binding posts, better capacitors on the tweeters.
The Suprema II monitor was just an improved version of the MMDC (with bass modules but for this comparison we will only consider the Suprema II monitor section). I would bet the MMDCi is 99%-101% as good as the Suprema II and for less money.
They use the same main driver.
They both have ZERO crossover components on the main driver.
They use a simple cap on the tweeter.
if you are considering the Suprema II's because they have integrated subs then that could be a very good option. The sub towers are handsome and integrate well with the monitor section visually. I can't say how they sound together as I've never been able to hear a set so maybe I'm way off here.
The newer Royal Virtuoso is pretty much the MMDCi with an even better posts and cabinet construction still (reduced diffraction from the rounded edges). I don't see how going back to '98 Suprema II's is a step up from the current improved MMDCi. Sometimes this is true with certain speakers but maybe I just need to hear the Suprema II to understand if this is better. I just doubt it since the main driver is still being used and the same tweeter just without ferrofluid is still being used. It's a Seas tweeter. Nothing fancy really but I do like the silk dome sound.
I think what would be the ultimate solution for wanting more bottom end is to get a pair of sealed subs, a good crossover with very steep slopes (24-48db/oct), small parametric EQ for the subs to tame peaks and cross the MMDCi's over at about 80-100Hz. With a very steep slope the integration should be quite seemless with some adjusting...it will take time to get it right but once you do, the MMDCi's will be improved more than you could have thought.
IM distortion in the MMDCi will be greatly reduced and the sound will improve substantially. This is because if you are asking the main driver on the MMDCi's to reproduce frequencies from 40Hz up to 4k,5k with the same clarity and SPL levels you are going to get quite a bit of IM distortion in there that just isn't pleasant.
Low frequencies require either greater cone area to move the same amount of air for any given SPL or greater excursion to move that same amount of air to reach the same SPL. So you see where this is going...if you ask the MMDCi woofer to make bass it will. If you ask it to make bass and midrange it will however at a price. That is increased IM distortion. Take away it's extra low bass duties and it will free up the midrange greatly. It will still have that MMDCi sound but cleaner and more dynamic.
The subs will handle all the sub bass needs and when properly placed in the room with bass absorption and a slight taming of any major peaks with the EQ, you will have one smooth sounding system with much greater dynamic impact and headroom. And again the midrange will be freed from the colorations generated by long excursions...
I know from personal experience how MMDC's sound with very musical subs. I was at Aris Audio with my old MMDC's and was able to hook them up with a pair of Vandy 2WQ subs. Now the sub integration was very smooth, albeit it was only a 6dB/oct slope, so not as much bass was taken away from the MMDC's but even that setup proved to me that subs should be the ones handling bass duties.
I love how the MMDC's do bass. They sound great on their own. In the right system and room they are all you would ever need/want most of the time. But when I heard how much more dynamic they became and even less colored with subs handling the lowest notes well I became believer in higher quality subs with hgh quality monitors.
Anyway, this is just my 2cents ...
