SDA SRS 2 Power Requirements

Hello,
About a year and a half ago I acquired a pair of 1986 blade blade SDA SRS 2 loudspeakers. I had a little trouble getting sound out of them at first as they did not have an inter-connect cable. I purchased a 220 watt max Yamaha receiver to "get by" as I am not quite in the audiophile budget. Everything works fine and all the drivers move and there is sound coming from the tweeters, but I have noticed a lack in bass output. It is by no means extreme and there is still a decent amount of bass, but in many instances my passive radiators are put to shame by an 8" Klipsch ported sub. When listening to songs with a lot of drum hits such as the drop on "in the air tonight" by Phil Collins the bass drum hits are heavy and full. I assume because all four active drivers move out giving the passive speaker a big "punch". The issue arises with what might be described rumbling bass and organ pipes. There are many of these low tones that I simply cannot hear let alone feel. I realize that the passive radiators won't move as much as an active woofer but from what I've read they should be able to hold their own. As I said before all the drivers are moving including the radiators, putting my ear in the general vicinity of the passive radiators brings a kind of painful pressurized sensation regardless of the type of music. I assume that they are putting out extremely low bass. I was wondering if it was a lack of power causing the problem because I know that the max of 110 watts per channel I can give then now is about 1/2 of the 200+ watt recommendation. I've also been told that it's just how the radiators are and depending on what I want, the loudspeakers might need to be supplemented with an active sub. Is this the case? I was looking at the Crown XLS 1505 which would get me up to 525 watts a side on the 4 ohm load. I assume that the amp would be enough as far as power goes but I am also open to suggestions!