Really need some help finding a full range speaker

I've thus far been on the sidelines here, but I must say I've been very impressed with the knowledge many of you bring to this forum . I'm hoping to tap that knowledge, if I may, and get some help finding a new pair of speakers.

I currently have a pair of Paradigm 75f's and I've been very happy with them. To me they sound neutral, fairly accurate and exciting to listen to. But with just a pair of 5.5" drivers providing bass, they are lacking seriously at the low end.

I"m driving my Paradigms with a CJ LP70S which puts out 70 watts per channel. It has no trouble driving the 75fs but I'm inclined to buy a more efficient speaker this time around. I"m also very interested in maintaining or even improving on the accuracy and neutrality I"ve been enjoying with the Paradigms.

I'm searching in the used market and looking for a pretty significant upgrade. I'm very open to vintage options and am searching in a fairly wide price range from $1500ish (used) up to around $5k. I'm concerned about not having the opportunity to demo the speaker before I buy it, but am highly motivated by the cost to value ratio available with used speakers.

One final concern is size and aesthetics. My wife is simply not going to tolerate a tower speaker bigger than she is (or I am for that matter) and more flamboyant designs are not welcome in the listening room that doubles as my living room. I'm hoping to find a fairly straightforward looking speaker that's large enough to accommodate bigger drivers but doesn't completely overwhelm the room with their size.