Will Merlins be too much

The TSMs sound great in rooms of your size. I've heard current production TSMs sound excellent with moderately priced solid state gear. Haven't heard your Nak. components, but if it isn't a good match, you can get good compatible amp for less than you probably think.
Talk to Bobby@Merlin. You will be amazed at the personal approach he will take to understand your needs & preferences. You will be hard pressed to find another speaker that will give you as much long term satisfaction as the Merlins. Cheers,
Spencer

Lindisfarne comments may be accurate about the old Merlin's, I am not sure. But I can tell you he is "wrong" about the current Merlins. I have the TSM-MX's, in a small 10 by 12'ish room, and they are anything but sterile. Drop Bobby a line, he is very approachable and will let you know about your situation. Just be aware that they are very revealing and will show any weaknesses in a system.

Regards,

lindisfarne, what model tsm did you have?
and how many years ago did you have it.
newer models can be used with a much wider variety of associated gear.
yes there is a reason why joule is used at shows and it is not because it is the antithesis of the merlin sound.
a lot has happened with the newer models.
bobby@merlin

Yeah, I have a pair of vsm-mms, and let me tell you, they are ANYTHING but sterile. They play any type of music I throw at them with amazing realism and "rightness."

Jason

I've been using my Merlin TSM-MX's in a 13x19 room with Arcam AV gear. I can assure you they are very musical, not at all sterile even with these modestly priced electronics and cabling. I also have Joules in my other 2-channel room, and yes, the TSM's with those amps are outrageously good (musically rich, but still tonally very neutral).

In a 10x12 room you could probably go on the diagonal if it makes sense from a furnishings standpoint. That would get you back a little further from them and maybe help the bass.