What 4 subwoofers to buy?

I am using a pair of Klipsch Cornwalls from 1984 and a pair of Klipsch Heresys stacked on top of the Cornwalls. I recently bought a Klipsch R-115SW subwoofer and could not get any satisfaction from it. Too many room placement issues. So I kicked the subwoofer out of my listening room, being that I get better results all around without it.But I still desire an upgrade on bass performance and would not complain if overall speaker performance was increased. I have been reading alot  lately about the DBA thing, and without even trying it, I am positive that it will be the best thing for me. But I have come to a brick wall sort of speak in my search for which subwoofers to buy. I am not rich, so buying 4 of Rels best is out of the question. I know that Miller Carbon is always saying that quantity over shoots quality, but when I use manufacturer subwoofer mating tools, the results always comes back with their most expensive subwoofer for my system. One of my main concern is will 4 lower end subs be an enhancement to my system? I was going to buy 4 SVS SB1000s because they are very good priced for the quality and they also have the high level speaker input which I will need for hooking up to my vintage integrated amp. But as I was researching all of their other models, I noticed that only their 1000s had these hookups? I emailed them and asked why their other upper models did not have high level speaker inputs? They said that none of their customers have expressed the need for them? I am not sure how to understand that? Maybe most of their customers main interest is in home theater and not 2 channel stereo? I do not know? This is where I have come to a stand still in buying my 4 subs. Will 4 lower end subs work for enhancing my system or do I need to go higher up in the chain as far as quality is concerned? Any ideas, knowledge, experience and or opinions will be greatly valued. Thank you.