I replaced the stock SDA 16.8 mH inductor (2.7 Ohms DCR) with the Erse SuperQ 17 mH inductor (.4 Ohms DCR). The overall speaker DCR decreased from 4.3 Ohms to 3.1 Ohms.
The results were very positive:
At first I thought bass response decreased but more listening on many different recordings and test tones revealed the low bass was still all there but the lower mid-bass decreased. The best description is the bass tightened up, became more dynamic-accurate and less lazy, muddy or boxy. A solo standup bass has 95% of the impact as before but is MUCH more defined and tight. You can hear the fingers on the strings and the movement of the hand on the kneck. Previously these were obscured by some slight muddiness and overhang. The tired cliche about air around the instrument does indeed apply to the bass now.
The soundstage narrowed a little but deepend by the same amount. Hints of out-of-phase hoaky effects dropped dramatically. There are still behind-you surprises but now they are more anchored and less phantom-like.
The midrange jumps out now. My impression of the 1.2's has always been "layed back" and a little heavy in the 700 - 200 Hz range. Bells, chimes higher organ notes, accoustic guiter strings, and other lower midrange sounds now pop with surprise.
The center is more defined and anchored. Upper midrange and into the lower trebble is more impressive and natural. I think this is due to the better damping and lower overhang from the better controlled SDA MW's
On very wide recordings there is no hole-in-the middle. The soundstage is more evenly distibuted across the front. Before the mod, if I walked toward the speakers, while a solo vocal was playing the center soundstage began to fade until at the plane of the speakers, it was as if you were standing in a void. Now the vocals are clear and only at the speaker plane do they sound reduced but never absent as before.
Ok now for the bad. The SL2000's seem a little bright to me now. They are acceptable but with the improved midrange and tighter bass, they stand out and are a little annoying.
For $68 this a one heck of a good mod. I was prepared to be dissapointed but alas, I will not be sending the inductors back for a refund.