To me, the differences from these subs should have been minimal and differences more likely related to positioning and setup and eq....but I wasn't there.
As far as the Sb12 plus vs PSA, I haven't compared them directly mainly because of the sequence I bought them.
I had the SB12 Plus, then the Rythmik E15HP, which totally took care of my issue with the SB12 Plus. I wasn't looking back so did not directly compare them. Later, I bought the JL Audio E112, thinking it would be the ultimate sub for me. It sounded more or less like the SB12 Plus. That truly flummoxed me, so I did a thorough test of dual E15HP vs dual E112.
Using two receivers and two pairs of Energy RC-10, I set up Audyssey on both and compared them. This was overkill as far as level matching, etc. The difference was far too great to need that much attention to the details, but I wanted to make certain. Next, I swapped the position of the subs. I initially had the E112's sitting on top of the E15HP's, so then I put the E15HP's on top of the E112's compared them, then, just in case, I reran Audyssey. Wanting to make sure I left no stone unturned, I then reset both receivers and manually set the crossover to 100Hz so Audyssey (which is not always consistent) was out of the picture. And, since I had already gone to all of this trouble, I felt obliged to once again swap the position of the subs.
No matter what, the E15Hp sounded clean and the E112 sounded bloated, and I am talking a difference where they do not have to be side by side to hear it, one sound good the other does not. Changing the settings and the locations did change the sound, but these mdifferences were slight compared to the differences between the sub manufacturers. The only question is whether the recording has bass recorded too loud, but that was easily answered by listening to classical recordings. One explanation I can buy is that with room gain, the E112 had too much deep bass for Audyssey to contain. I have a largish living room with vaulted ceiling open to the second floor, but the subs were about 18" from the back wall and 4' from the side walls. If you look at charts measured in room, it is common to see 15dB or more of room gain in the low 20's. So a sub that is flat in an anechoic chamber might be 15dB too hot in room. I think Audyssey can only manage around 10dB.
Another thought is that the Q value for the E112 driver is not where it should be, but I am not that technical to do more than guess at this.
I bought the PSA's after hearing them at a friends house and realizing they had the same general character as the Rythmiks. It is to my ear a clear difference between wrong and right (though I admit "wrong" can be a lot of fun when watching a good action flick, but not for music).