Hi everyone,
Just to clear the air, neither Mark Schifter nor Danny Richie have anything to do with the Mark and Daniel line.

Regarding subs, you will have a hard time finding one that can keep up with the bass drivers. Once you get up to the Aragorn line, no sub should be necessary. I just received the Aragorns last week, and have been breaking them in. Its quite an interesting design, with a "trap door" on the bottom of the speaker that once removed, it couples to the Aragorn "bass extender" stand to lower it's f3 to 28 hz. I do not have the stand yet, but I could swear I am getting in the lower 30 hz "in room" response. They are much like the SP Tech (which is one reason I chose the line) in that they have a single driver that is crossed low and covers most of the audio band. Instead of a waveguide, M&D went with a modified Heil Air Motion Transformer. It is a type of ribbon, folded like an accordion, where the element contracts and expands to "squeeze" (for lack of a better word) the sound out from between the elements folds. The HF driver of the Aragorn has 60 times the surface area of a 1" dome tweeter, meaning not much movement is needed to generate serious sound pressure levels.
The bass driver is quite special too. Remaining linear at high excursion levels. Playing extraordinarily deep bass for their size. They traded some efficiency in order to maintain the LF performance even at low volumes. SP tech did the same.
What is different about the Mark & Daniels is they squeeze this performance out of a much smaller speaker. So for my customers who don't have the physical space, the M&D is a great way to get big sound out of a smaller speaker. I would put the pair of 8" M&D bass drivers in the Aragorn up against a decent 12" sub for bass extension. It may not reach the triple digit spl of the sub, but it will go as low in my opinion.
I am more than likely going to have a series of mods available for the Maximus, and Aragorn speakers. Such as upgraded crossovers, Bybees, and Speaker correction algorithms for Perpetual Technologies P-1A SOCS (my day job).
I am wating for the new Sapphire to come out, and will probably carry that in Lieu of the Ruby.