What kind of music are you playing & how loud, do you have stands and how big is the room? Also, how lively is the room (clap test)? Budget?
I had to go through a similar situation for my bedroom and due to the wife factor had to keep the speakers near the wall (16" from face to wall).
A couple of things I realized was how easy it was to bass load the room, greatly reducing the quality of sound. I was trying to improve the sound in my room so I tried all sorts but most speakers were too big, monitors with a 7" woofer were overkill, they sounded terrible (my room is lively & 16x14x 14'H & listening 10' away from speakers).
You'll find that pretty small monitors will give the best results. For my room, at the end of auditioning many speakers I ended up very happy with Totem Ones (not for you) even though they prefer being a bit farther away from the wall.
I also bought some JohnBlue JB3's on Audiogon for my girlfriends office. Surprisingly, These blew me away with there sound. I hooked them up in my bedroom system to check out and was very happy with the sound, I would pay twice the amount for them. They completely disappear with an awesome soundstage, the mids were beautiful, very musical. Bass wasn't bad either for such a small speaker in my room but you can't play them loud (party level) as the sound gets compressed and falls apart. These could work quite well for you.
Your amp is considered neutral & 100w@8ohm so that helps. Look for a forward venting or sealed monitor. Remember that keeping the speaker close to the wall will really hurt soundstage and depth, there's not much that can be done to avoid that issue. When comparing different speakers, keeping the front of speaker at a known spot, I did notice the smaller/shallower the speaker was, the better it did with this issue, it helped that there was more space between the back wall and the back panel of speaker.
The Harbeth P3ESR are bigger than Totem Ones with less bass, they are recommended to keep back panel 11" away from rear wall. They are a very relaxed sound, they are not fatiguing in any way. This can be a good thing for a bedroom system. They are pricey but beautiful finish (go for Rosewood). 83db@6ohm will require juice but you have enough with the Quad.
I'm having a hard time at this moment remembering at the top of head recommending other speakers. Take a look at the J.M. Reynaud Trenté, these were a pair I kept coming across as a potential candidate.
The LS3/5a can be ruled out, they are not a bookshelf type of speaker and recommended to keep well away from walls.
I also recommend a very good solid stand/base or if you have them placed on a table, make sure it's very, very solid. I only mention this as I keep seeing bedroom systems with alternative ways of positioning speakers on desk, , benches, tables, weak stands, shelves...etc. Speakers near walls can sound boomy and you want to try to keep that to an absolute minimum, solid non-vibrating bases will really help your speakers sound nice & tight.
I'll now step off my soapbox. Cheers