Which REL sub, R528 or B2

Bo1972, it makes sense what you write but I'm looking for a sub that is musical first of all, I want to implement it in audio system and there are not many subson the market making "music" . Majority are just headbangers, exellent subwoofers for HT but not for music. Example, my Velodyne that I had. It's harness was to much for a long run. But it was great in HT, great.
Big advantage is REL connectivity also that makes them more versatile, useful. Again, when I got my Velodyne I thought why the heck I can't connect HT amplifier and stereo amp at the same tame. Maybe Rel is not the fastest in the world but all the virtues plus very good bass they produce make them one of the best options for my purposes.
Thanks for your comments anyway.

My used RELQ150e cost me $200 a couple of years ago, and remains my all time "bargain component score" champ, about which I am (maybe annoyingly) smugly satisified. Note that speaker "speed" is another one of those psuedo techno terms that means nothing in the real world of experienced listeners, bass players, and otherwise non biased individuals lacking a retail agenda.

Another example, in the past I sold many Rel subwoofers. Like the Stadium III. It was okay, but still not that fast. We did compare it with a Monitor Audio GXW-15. This one is also a lot better in timing. I sold this Stadium III and he bought a Monitor Audio. If Rel would make a better sub, I would have sold this. At a show were I used the Monitor Audio PLW-15. People were amazed how fast it was. They all thought they were only listening to speakers without a sub. Many of them never heard this quality in stealth level. I think most of you are still at this level. Time goes on, so does speed and timing for subwoofers. For a long time I sold normally Rel. But these days you can get better!!

I rest my case.

Xti16, what crossover frequency have you set up with C1? How big is your room?