It's not as simple as out and out size where standing waves are concerned, what you're trying to avoid is dimensions which are the same, or multiples of other dimensions - the length is almost twice the width, although a metres difference would be enough not to be a direct multiple. What's the height?

I think a nice pair of 5Ks would sound great for a start, and maybe for a good long time! The beauty of them is that you'll pretty much get what you paid for them second hand if you ever decide to move them on and upgrade. I think they'll be a good move from Naim/PMC in terms of adding some naturalness and warmth, while still retaining the dynamics and rhythmic drive you're used to. The risk with the. 5500s is if they don't gel with the room, or you aren't prepared to spend time and redecoration with room treatments in the form of bass traps, you might get too much bass richness which will translate into perceived 'slowness' and boom - the opposite problem to the one you're trying to get away from now?

I speak as someone who came from Naim/Avondale systems in the past and now greatly enjoy certain Meridian gear much more wink


HC: 861v4/ID40/LPS, DSP5000, DSP5000VC, DSP3100, SW1600, HD621, Oppo BDP-105, Sony VPL-HW55ES
2-Channel: Oppo BDP-105, TEAC VRDS-7/Trichord Clock 3/PSU, 551, Quad 303, Harbeth Compact 7ES-3, Kimber cables, Russ Andrews mains and supports.
Previous Meridian: 5000C, 5200SL, 7200.2, 6000, 562V.2, 568.2mm, 800v4, 808.2i, 818v2/v3, 861v8, 502