Looking for a Speaker in the $15,000 Range

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.

This is way above my league (my whole system cost $5000), but it strikes me that if you're completely happy with the Quads except for the bass and sense of scale of the sound then you should try to get a home demo of a good quality subwoofer, like a higher end REL, or audio-physic.
I was in the same situation with my system (based around spica-angelus, which have fabulous midrange and imaging, but can sound a little thin and lacking in dynamics) and the addition of a REL sub completely fixed my system. Now orchestras sound like orchestras.

It's worth a try before swapping speakers, and would probably cost you around $3k for a good sub.

I would suggest either as speakers that might let you get closer to the music, particularly in soundstaging, but have some concerns about the amp/speaker match. Unfortunately, I doubt that the pairing of Thor with Avalon will allow much above moderate listening at best (but it should be pretty magical if quiet!). The Thor/Kharma combo will probably have more luck. I have owned speakers from both, and personally prefer Avalon but loved the Kharmas as well (and plenty of A-gon regulars would feel the reverse).

... there's my $0.02 (MSRP)

Jacob

The Kharma 3.2's should definitely be added to your list and listened to. Let's say when I put them in my system after having the Wilson Sophia's, and a couple of other fine speakers they brought new meaning to the word bass in my very large (55x44) listening room. I had Dynaudio Temptations before that, and they had better usable bass than them as well, not to mention better musicality, liquidity and a MUCH larger soundstage. I do have to say that this effect was much more prominent with SS (Bryston) than tubes (Tenor). Tubes with the Kharma's were sublime.Can't speak to the WP7's which I haven't heard, but compared to the Sophia's the Kharmas were just in a different league re transparency and spooky "they are here" imaging.

Get a pair of Klipsch cornershorns. Take the money you save and pay for one of your grandkids's college semesters!