Speaker Upgrade

How big is the room?

The room is 22x15

What are you looking to improve upon? I read the review of your speakers,the look to be a high value product. Have you considered the 22L Subwoofer? While I havn't heard them, the typical improvements gained from subwoofers might just be enough to allow you to retain the qualities that made you buy the 22's in the first place.

I think the Quads are the weak link in my system. I have upgraded everything else since I bought them. I am looking for deeper low end and smoother mids and highs ;.) I forgot to mention Acoustic Zen Adagio's which are in my price range(used)I heard the 22l sub when I bought these and was not impressed.

Have you heard the Response 2.5? I heard the 2 in 1996....nice speaker ,but not if you need solid LF performance. At that time the 4's were the full range speaker.Do a search and you will find a pair of 3's in your price range.I bet you don't want that pair due to age(10 yrs.)
Before you take the bath on selling the Quads,is there another subwoofer (Sunfire,Vandersteen,Hsu etc.)? Unless you feel the Quad is just not gonna cut it,trying to integrate a subwoofer will offer a decent upgrade path. As a last resort,do an Audiogon search for Audio Physic Virgo III.
It's a little over budget,(No affiliation with the dealer!!)but this is one of a handfull of "deal" speakers at something like your $2500 budget.