the original LSii's had issues... I am not sure what it was exactly.
whether it was a resonance or a bad XO network, they were very harsh and extremely fatiguing when I first got them. I was distraught at first, but I decided to try and work with them because they did have that tight focused LF sound.
firstly, I just listened to them at slightly lower volumes than I was used to listening to my Cornwalls... that helped. then I started to get used to the extreme resolution and clarity and began searching out alternatives to source material and front end amplification and preamp. That lead me away from class D and into Tube amps, and that helped tremendously as it completely changed them into a different animal. After that I kept at it and tried better end preamps and tube amps and it got to be really good but they still could not match the 70ths.
when the great deal on the 70ths came about, I jumped at that chance and as soon as I set those up, they were wondrous and rewarding. It was like a completely different speaker with the similar attributes to the original LSii's. I was so surprised that I compared every aspect that I could between the two speakers, but they appeared to be very very similar... the only thing I could see was the difference in the XO, and a difference in the raw materials of the case/speaker wall. The original speaker had a very large grainy loose MDF when looking 'on end' from the exposed back, and the 70th's had a VERY smooth and much finer and tightly packed grain material finish 'on end' and to me it looked as if they had changed the MDF formula... but I was assured it was the same by the community. A knock test on the speaker walls also revealed an audible difference between the two speaker types in terms of their Timbre.
original LSii XO
70th LSii XO