I have a BBP34. Its a magnificent bass. I love it. Great sound, top notch components and build. Furthermore, as far as I can see, everything that Yamaha make, from mixing consoles to motorbikes are well thought out and supremely workmanlike devices. They do what it says on the tin very very well for a very very long time. All that being said- and I hate to sound cynical- what the IRA treatment boils down to; They take the bass, shake it for a bit (albeit at various specific and pre planned frequencies), and that is meant to make it sound better? I mean, who am I to judge.....?