used speaker recommendations


I'm relatively new here.  Am in the process of upgrading a 2-channel stereo that is currently: Wharfedale Jade standmounters, Cambridge CXA-81, SVS sub, Bluesound Node2i streamer, Graham Slee phonostage, refurbished Dual 1228 with NOS Shure V15-III/Jico hyper-elliptical, various Pangea cables.
I like the "british sound" having around the house both Mission and Celestion speakers.  Nothing too bass-heavy or overly bright.  I think musical, rich, warm, detailed but not fatiguing.  Type of music I listen to: Argentine tango (Go-tan Project), Van Morrison, Sinatra, Ellington, Pink Martini, Chicago blues.  When in the mood I love the Rolling Stones. 

The room is small, 15x13.  I am currently building some tube traps and acoustic panels.  WAF necessitates standmounters.
Budget is $1500, tops.  New, I would probably stay with Wharfdale.  Lintons, perhaps, but the reviews of the Evo 4.2 are uniformly good.  My real question for this forum, though, is on the used market because I am unlikely to be able to audition most of what is offered for sale.  There are a number of interesting options in my price range just looking at Audiogon and USAudioMart.   For example: KEF LS50 and R3, ProAc Response 1sc, Spendor SP 2/2 and 3/5, Tannoy HDP/315/8, Revel Performa M.20.  Then there are the non-british brands that might fit the bill like Sonus Faber Concertino/Electa/Venere/Luito/Minima.  Yikes.  Any thoughts would be greatly appreciated.
treepmeyer
I find it very interesting to figure out at each step what the weakest link is in my stereo, and then assess the options for addressing it.  I have to say that I started using the Bluesound DAC, then got a Pangea coax to bypass it and rely on the Cambridge CXA's DAC.  That was a major improvement.  I don't doubt that there are a range of  better DACs available. 

My guess was that room bass control was first priority, then speakers to take better advantage of the rest of my system, but your comment has given me pause to reconsider.  Food for thought.  Thanks.
So....I spent some time listening to the Jades and I am curious what the issue is.  The Jade 1s were maybe a little lean, but the Jade 3s were amazing.  I found them warm for my taste but with brighter amplification, they are brilliant.  A lot of the speakers you are looking at are not necessarily going to be better than what you have.  They will be different.  

Different might be better, but I would need to understand your challenges with the Jades before making a recco.  That is a VERY good speaker that punches above its weight.  I would not say that the Kef LS50 is inherently better.  It is just different and in some ways (bass response) it is worse.  
The current speakers are Wharfedale Jade standmounters.  For DAC I use the CXA 81.
I have wharfdales in my theatre, I can't recall the model they were about your range and I run acoustic zen adagios there is no comparison honestly (they are like 4500 5k new)  .If you go used I highly recommend you investigate Acoustic zen ,adagios are usually a little more used but there stand mount monitors and eventually a couple subs would blow you away imho