Best Used Speaker Under $4,000 w/ Respectable Lows

I was once a member of the audiophile community (Some of the older Audiogon members may remember me) but had to step out for a bit do to life changes. I am thinking about stepping back into it in a limited fashion with the system configuration listed below. I would love opinions on what used, $4000 or less, speaker would best suit the following system. Note that I would prefer NOT to bi-wire and would love something with a respectable low end (A full range speaker would be nice). I tend to treasure transparency, neutrality, high end extension, speed, DYNAMICS, and tight driver control / integration in my speakers and leave bloom/coloring/musicality to the amp. I also prefer speakers that play very well at low volumes with medium power amps. Thanks for the help!

Transport: PC with Windows 7 / WAV Files / Foobar / Lynx AES16 PCI digital I/O card

Dac & Preamp: Berkeley Audio Design Alpha DAC

Interconnects & Speaker Cable: Nordost SPM

Amp: Sim Audio Moon W 5.3
Your room size is an important consideration. What do you mean by medium

Off the top of my head, irrespective of the above:

Vandersteen 2Ce
Vandersteen 3A Reference
Silverline Sonata II or III
Von Schweikert VR4 Gen III HSE
Von Schweikert VR4 Jr
Klipsch Klipschorn
Coincident Partial Eclipse II
Gallo Reference 3
I would try to find a pair of Focal 1027be speakers on the used market. They are excellent speakers. It's fair to call them reference level and lately I have seen one or two sets selling for a song. Furthermore, they are not biwireable, and are full range, as you said were your preferences. Good Luck!
An Audio Note E silver speaker would fill most of the criteria listed. I feel mine are very open and pure. I have not heard them with SS however, usually they are run with tubes.
if you have a nice amp in the 200 watt area, try the totem mani 2's.
Hyperion 938 or 968.
I would be looking for Dunlavy scIII,scIV,scV or sc VI's based on what your room size is;probally one of the best full range speakers ever made.
B&W Matrix 801's ... well under your $4000 limit

Aerial Acoustics 10T's

both have more than respectable lows
If you stretch your budget just a bit (~$4500 used) you could get a pair of Vandersteen Quattros. These speakers have internally-adjustable subs (with amps) that will provide full-range low-end. The rest of the speaker is also excellent. One other thing about this speaker that violates your criteria - Vandersteen recommends biwiring. I think you'll find the trade-offs very worthwhile.
Legacy Focus 20/20 or Coincident Total Eclipse (used). Both are full range, dynamic and fun. The Coincidents are a bit more accurate but the Focus are amazing in regards to slam and dynamics....both are within this price range on the used market.
Zu Essence at their new price is in your range. Read this monts Stereophile report on them.
the choices are infinate.
Anything by Talon...
the choices are infinate.

I disagree...choices are way beyond infinity
I second the Aerial 10Ts, provided you have an amp with at least 200 watts per side. I still have my 10Ts, and even though they have been relegated to the fronts for our HT, I still listen to 2-channel in that system a couple of times a week, just to enjoy them. They amazed me for what they could do at their price point in 1998 when I got them, and even though the technology they employ is somewhat dated, they still amaze me. You can generally get them in good shape on the gon for between $2500 and $3000.
When I read your description it fits my tastes exactly. I would recommend Proac Studio 140s or the D18s.
Just a bit above your price buy it is "obo". Way beyond your expectations.
I own a pair of Salk HT3. It is the best speaker I have owned or heard. Obviously there are tons of great speakers out there at that price point and there are great people on this site that help you make the right choice.

I spent a year looking for a replacement speakers and settled on the Salks. It was very frustrating at times but well worth the time and effort I put into it. Take your time so that you can be happy with your choice for a while.

Happy hunting.
I currently have B&W 801 series 3 speakers driven by a pair of McIntosh 501s. The lows are abundant, coherent, and most important they're great listen to.
I spent some time with Jim Salk at his home listening room. He is a gracious host with a very realistic listening room - meaning odd room size and no room treatments. Listening in this environment I can say for the money his speakers are a great value. I was able to listen to the Archos open baffle, HT3, and Song Towers, as well as a prototype of a new model Salk will be introducing (or by now may have introduced). I could easily live with any of them. I'm sure there would be something in the Salk lineup in your price range you would be pleased with.
Anthony Clio09
You sure get around ! yes, I agree Jim's speakers are very good value and a sonic homerun for those looking for their next speaker upgrade
Merlin VSM-MM is a knockout,cannot go wrong,good luck,Bob
Pat, it just so happens the company I work for has a corporate office in Troy, MI and I get there once or twice a month. Jim Salk lives nearby, although his shop is in Pontiac, MI. It was a matter of convenience.
I recently got a pair of Tyler D2's, he sells used for about that price. Everything you are describing is there - awesome speaker. Tremendous bass, dynamic, neutral, non- fatigueing, and solid (as long as you don't mind 140 lbs!). The quality of the bass reminds me of my old REL Storm subwoofer, and that's saying a lot.
"I tend to treasure transparency, neutrality, high end extension, speed, DYNAMICS, and tight driver control / integration in my speakers and leave bloom/coloring/musicality to the amp. I also prefer speakers that play very well at low volumes with medium power amps."

High end extension
Dynamic (contrasts)
Play at low volume without losing the above

The latest Merlin VSM-MM or MX might be what you are looking for. They certainly excell in all the areas of your criteria, check the archives and reviews. You will get the best customer support in the business whether you buy used or new. Bobby Palkovic is always there to help you every step of the way. In any event you should not buy anything without listening first.

There are many speakers that might suit you and there is nothing clear cut, one man's love is another's loathe.
Speaker choice is a very personal choice, more so than anything else in the chain IMHO. You'll get plenty of suggestions but you really have to do your homework. Good Luck and welcome back!
I had a couple pair of Merlin vsms and the mme. I loved the mids and highs but thw lows were a little weak in my main room which is 20 x 24 x 17. I used 2 jl 113's with them and that gave me some good punch.

My 2nd room has a 9 foot ceiling and they sounded much better there and i didnt need the sub.

I do listen to a lot of dvd's, concerts and movies and the merlins were great in that arena.
I suggest you check out the Abbey speaker designed by Dr. Earl Geddes. They are amongst the best speakers I've heard in my 30+ years in this hobby/obsession. When you take into account price/performance I put them at the top of the list. They punch all of the buttons you listed, except being full range. They are flat to 50hz and then roll off at 12db per octave. You'll need a sub or two to get the low end. IMHO, after having owned several pairs of full range speakers, the best way to get flat low frequency performance in most real rooms is multiple subs located asymmertically in the room.

While I've not heard the Merlins or the Salk's I can say they also have a strong following and appear to be a great value.
Usher Audio Tiny Dancer Mini One
I'll second the used dunlavy's.   Hard to beat a pair of sc=iv's or larger, full range and they just do everything well, fairly efficient, not sure what your amplifiers specs.   They can run on middle of the road  power , really shine with nice amplifiers.   John dunlavy understood speaker and crossover design on a very awesome level.

My goto affordable speakers are Monitor Audio, but with your requirements, maybe a TAD or JBL professional monitor?