Very good advice Geoff. If I had more room and my wife was accommodating I would consider Maggies myself, or if I have the dosh a pair of these http://www.analysisaudio.com/Omega.php (Planar speakers), I heard a pair at a dealers not long ago and they were truly outstanding and produced bass, or possibly the smaller EpsilonI have some experience with the challenge of putting together a good quality hifi system in properties where noise overspill is a consideration. My first serious Hi-Fi (1977) was a vinyl based system based around a Dual turntable, a Rogers A75II amplifier and a pair of Rogers Ls3/5a speakers. The choice of system was largely influenced by the fact that I was at university and living in the middle floor of a large Victorian terraced house in Hackney, The lounge was a great size with high ceilings and a large bay window but the sound insulation was minimal to the extent that I could hear conversations from the flat above and television from the flat below, not to mention neighbours on either side. The Rogers speakers, when wall mounted on long-arm speaker brackets were far enough from the rear wall to retain their imaging qualities yet largely decoupled from the house. The limited bass output meant that I could listen at reasonable levels and still enjoy the vitality of a musical piece. I find this to be a problem with many speakers, namely, that when played at low levels they lose what might be called a sense of energy or vitality. It is true that some large speakers such as the dual concentric Tannoys can sound good at low/evening level volumes but most speakers lack this facility.
The Rogers speakers survived through many upgrades and house moves. For many years I continued to live in small flats or accommodation where I was limited in how loud I was able to play music. My last accommodation before leaving the UK was a new purpose built one bedroom flat in Leeds near to Headingley. Here I had neighbours both to the side and below. The Rogers remained a fixed feature during this time although the rest of the system evolved. On the turntable side I transitioned from a Rega Planar 3 To a Linn Sondek LP12. On the amplifier side I moved first to a Rogers Cadet 3 valve amplifier and then to an Art Audio Quintet valve power amp with a Croft super micro preamp. A major transition occurred when I left the UK in the mid 90’s to work overseas and my hifi and all of my vinyl went into long term storage. Only my cd collection came with me.
Once overseas, the space and noise limitations were lifted. An unexpected benefit of working on international health in developing countries is that one tends to have a reasonable housing allowance or to be assigned decent housing. Freed of the limitations of party walls I acquired a series of floor standing speakers with much more extended bass output and far superior dynamics to the Rogers. I tended to sell up my system at the end of each contract and start again when I moved to my next project/country. When ill health forced my relocation back to the UK I bought a new detached property on the edge of Sherwood Forest and started my hifi journey again with a blank canvas.
As much as I love my LS3/5a speakers (I still have them) I have come to realise their dynamic limitations and their masking of fine detail and transients. Curiously, I was not so troubled by their lack of bass extension. Wanting to retain the natural sound of their midrange, my first purchase was a pair of Magneplanar 1.7 speakers. I mention the Maggies because I think that they may offer the type of sound you are looking for. Although the 1.7 model may be too large for your new accommodation, the newer models such as the LRS+ have a small footprint. They do require a powerful amplifier to drive them properly but your Sugden should be an ideal match. In my judgement the bass is more than adequate but more to the point it is fast and highly textured. Most importantly, they sound fantastic When listening at low levels at night. There are an increasing number of UK dealers where you can audition them and if you choose to do so I would encourage you to bring your Sugden along.
Alternatively, you might consider the Martin Logans that I mentioned earlier. If you are looking for a speaker to coexist with, rather than replace your Lintons, then these are ideal and could be placed atop the former for evening use. I bought mine on a road trip in the USA and carried them back as hand luggage. I bought them for a bedroom system both for music listening and for watching movies. I cannot recommend them highly enough. Without regard to their size, they are fast, detailed, dynamic and have a real sense of energy. They reproduce human voice better than most speakers irrespective of price. If I were moving back into a small flat with neighbours close by they would be top of my list. I see that there are now a few stockists in the UK so it's possible to get a demo.
I suppose the bottom line from this is that speakers like the LS3/5A which were long considered the ideal small monitor speaker for domestic use Have been eclipsed by newer technology at a far more affordable price. Mine cost £150 back in 1977. I see current production models sell for £2500 pounds. If you have the space, have a look at the smaller Maggies, if not consider the Martian Logans. Both will offer a satisfying sound at low volumes without bass boom or overspill. A rather lengthy post, but hopefully helpful.