Moving into an apartment with wood joist floors - worried about neighbors hearing

you don't need to change speakers all you have to do is get the Townshend podiums, they will stop all bass energy from going into the floor and coming back into your speakers and smearing the sound they're not cheap and they isolate down to three Hertz biggest upgrade I've ever done to my system, it sounded as if I went to much more expensive electronics and it also gets rid of pretty much all room problems, check them out

for the price of Townshend podiums, you can get decent subs and speakers with isolation feet, like the Arendals. 

There are two different problems:  1) mechanical vibrations of the speakers being transferred to the floor, and 2) sound waves from the speakers hitting the floor, causing it to vibrate and produce sound.  The first problem can be pretty much solved with mechanical isolation, as described in this video:  https://www.youtube.com/watch?v=LmZKKVQZx_Y

The second problem can be greatly mitigated by placing material under the speaker that absorbs low frequencies.  The guy at Acoustic Fields seems to know what he's talking about and claims carbon is the best (practical) material for absorbing low frequencies.  He sells various carbon based absorbers, including platforms.  The drawbacks are expense and an increase in speaker height.  He has some DIY guides too.

Several things come to mind here:

Very good tips on sound isolation/absorption.  Keep in mind that powerful low frequency sound waves are very long and can penetrate feet (yes, FEET) of sound absorption.  But,every bit helps.

If you love your Kivas, rolling off the bass via tone controls/EQ will accomplish the same goals as a bookshelf speaker in bass reduction without changing speakers.  Yes, you will not get the performance you paid for, but you'll get 90+ percent of it.

Using a meter to measure sound in your neighbor's space may get you technically, and legally(?) there, but sound pollution is a 'thing" and it's not cool.  Your neighbors have made an investment in their spaces and desire a living environment that is theirs -- not yours. A rule of thumb: if your neighbors can hear your system, it's too loud.  Sorry to be heavy-handed here, but I have first-hand experience with this on the "receiving" end.  Simple reading, polite conversation, and enjoying one's own personal music is compromised. 

This a bit of a tangent, on neighbor relations, and sappy but I’ma tell it anyway. When I bought my current place 25 years ago my neighbor marched right over , 1st day, extended his hand and introduced himself. He was retired and proly in his 70’s. My house was a bit of a fixer upper and the grass was hammered due to derelict sprinkler system. Neighbor’s lawn was well kept. After he saw me working on the sprinkler and the rest of the house, he came over and offered to help. Both front and back control valve manifolds were trashed. While I was at work he went to a pipe fitter and had copper manifold sweated up and installed them, never ask for dime. That forged the foundation of a friendship with a family that lasted until his passing. Since then I have repaired heads, lines and valves over the years but I have never had to touch that copper manifold and we get zub zero here in the Rockies. So every late fall when I winterize the system and I look at that manifold all incrusted with grime and dirt , I think of him.