Disclaimer: I sell Quad, Pass Labs and Wolcott.
I would first take a look at trying a good subwoofer in your setup. I run my 988s alone or or with a storm subwoofer in my 25 x 14 vaulted room. I use them primarily with P220 Wolcotts. I prefer them alone for acoustic and vocals, but with the sub for more dynamic music. I'm in a new room now so I don't think I have tuned the subwoofer placement/damping optimally yet. I'm still getting a feel for the room and sound treatment. The real trick is to get them matched fairly high up in the low bass without causing interference to the midrange. When set up right, it actually improves the midrange considerably.
The best subwoofer's I have used are the Audio Physic Luna and the Rel Storm. You need something with speed and clarity, so the smaller high quality subs are best. The Storm is a little better because it allows you to specify an exact crossofer. The AP only allows 32.5hz and 46 hz but is extremely fast. I cross the storm at 38hz. The 988's are down 6db at 36hz.
I have owned the 5's, the Eidolon, and have heard the Wilson's and Kharma's. I went from the 5's to Eidolon's to the 988's. These are all world class speakers.
The 5's have the best low bass of the bunch, will work well with your medium powered amps, but will also dial out a considerable amount of midrange clarity. The 5a adds this back a bit. They are laid back like the Quads which may appeal to you. You will get the best bass out of these because of the integral subwoofer. Their high pass filter makes the 5 look like a monitor to your tube amp, so there is much less strain on your amps. I found I needed to biwire for good performance.
The superb Eidolons will not work with your amplifiers. I found they worked best with a 300w+ solid state amplifiers. Their bass comes alive at that point.
The Wilson's are world class speakers as well. I've heard them sound world-class with VTL and BAT VK-150SEs. They seem to sound best with ultra-high resolution tube gear.
I have heard the Kharma's at Jtinn's and feel they have one of the very best midranges and extraordinarily fast bass. They were driven with the 75 watt Tenor's/Meitner and formed one of the best system's I've heard anywhere.