As HH so cogently puts it, that is utter bow locks! Whyever would the use of a Hydra invalidate warranties or insurance? They’re just perfectly standard Naim mains cables bonded together.
I don’t actually think that a ‘good’ mains block is better, but get yourself to Grahams in Canonbury, if you can, and let your ears decide.
I agree, a REL sub seems like an obvious route to take, and you could get a good model for around your upper budget.
With the hydra you return back in the Naim Forum from the 80’s. Some will also tell you that a DoLorean is the best car you can purchase. 
Seriously, you should consider a Furutech, a Chord S6 or M6, An Eros Titan or a Music Works , at the level of your gear.
I could not disagree with you more about the Hydra, but there we are.
Definitely. I’ve only not listened to the Furutech (but you should be lucky to do so soon!!: ) - from the rest, I would say MusicWorks would probably be my choice if looking for the most natural relaxed sound, M6 for best lower end (and indeed quietest background), Eros and S6 I remember as similar level, more lively and both also very good.
Yes, I’m siding with room acoustics and speaker placement. Those speakers look big enough to move the air in your room. Powerlines etc are superb, but are unlikely to add bass slam in any significant way.
Are you seeing the drivers move on the speakers with low frequency content… but still not feeling it… when listening… I would check amp speaker matching… but assuming you have the power and you are seeing the drivers move I would explore room and speaker position. Slam is ultimately about shifting air and creating a low frequency pressure response… and here room, speaker matching is important, as well as ensuring the speaker is not working too hard against itself with the in room response.
Can you try a recording of a frequency sweep… you notice any lumpiness in the bass …or does it smoothly sweep down to the points you can’t hear, but you can see the drivers moving.
Finally I would say the ndx2 is not particularly fast or tight and punchy in very low frequencies and attack (I also own a ndx2)… so you might want to try a different or better DAC, and feed that with NDX2 acting as a digital streamer… however you should be able to get a bit of slam from it.
BTW, bass weight does not necessarily equate to bass slam. Slam is very low frequencies… (as well as higher), where as bass weight is really frequencies around 100 Hz through 300 Hz.
HH is right in saying that the SCDR would give more bass weight - as well as improved refinement and clarity, however it is considerably more expensive than a 2nd Hicap. When I had my 282 it was considerably better - especially in bass performance - with a 2nd HC DR…
Thanks. I guess I’m after a touch more bass weight then. Like I said earlier, if I had a treble and bass control on my amp, I just want to nudge the bass a little bit more (very small amount).
You really mustn’t mention treble and bass controls on the Naim Forum - you’ll have the late Julian Vereker (Naim’s founder) turning in his grave!!
Haha yes, and I understand why. I’m just trying to explain what I think I’m hearing and what I would like to hear. I don’t think I need bigger speakers or a rel sub, but if I had a graphic equaliser in my system, I would just nudge the bass control a smidge.
So you need greater bass output - if playing with room layout (speaker and listening positions) doesn’t do it, either buy a graphic equaliser which it seems is what you want (or better still a DSP box) …or get speakers with greater bass output.
AudioQuest Niagara 3000 or maybe a Shunyata Hydra D6… I also would replace All your power cables with good ones, I wonder why you wouldn’t. And a REL sub would make a huge improvement, REL S/510… there’s so much you can do to improve what you’ve got!
Larger speakers is the way to go.
Your electronics are great. A larger speaker gives you what you want.
Accuphase or Luxman integrated amp L Both have tone controls. I still think the loss of tone controls for the sake of high-end is a mistake for most of us. The only time they (must ) detract is in a room that already works optimally. Oops, have to have one speaker closer to a corner? or a couch just at the ideal position.Short of ideal acoustics, there must be times when judicial nudging will help most people, and if done in the digital domain…….
If you do that use DSP, and a program like REW to see what you’re setting up. But beware excessive boost - every 3dB uses double the amp power, and halves your peak headroom. If you have bass cancellation you need to do something else to fix, trying to boost it out being doomed to failure and a rapid path to speaker destruction.
I have a PMC 25 21i. From my desktop listening position, bass can be an issue. Fortunately, my RME ADI2 DAC allows me to tweak the bass/treble instantly depending on the music.
A very nice listening space and one which is well-stocked 
As others have commented (esp @Simon-in-Suffolk ), I think the bass and musical weight issue is more to do with the long space and listening distance from the 'speakers, as you have so many reflection points, obviously the moreso the further you sit away from the 'speakers – you look to be a long way back? Before you consider system/kit changes, I think some time spent understanding the space and 'speaker placement would be better.
I’d suggest some simple experimenting with listening position and 'speaker placement e.g. I’ve found that you often need to move to the focal point of the 'speakers, not away, as this can obviate issues of reflections and tightens everything up. The challenge here is one of domestic aesthetic and practicality, and the obvious prioritisation of how far you want to go in enjoying the system.
To give an example, my space is ~6.4m L, ~5M W and 2.4M H. The 'speakers are ~2.3M from the rear wall/glass, around 2.2M apart (centred), with the listening position ~3.2M away (forward from a treated rear wall by ~1M). Perhaps food for thought?
My room whilst smaller than that pictured above suffered “bass suck out,” it really messed with the cohesiveness of the sound……(non solid walls was my issue)
I tried multiple different speakers and active ATC’s were the only ones that worked…. 606’s sounded dreadful in my room despite being a great speaker.
To get the most out of my room I have stereo s510’s and treated the reflection points and corners with GIK panels.
Speaker placement in tricky rooms is part art and part science - lots of good material online so worth reading up before spending more money on hard ware.
Your room looks very nice so as others have said worth experimenting and if your room is tricky a good dealer can provide advice on different speakers.
My system sounded stunning in my old house but when I moved I couldn’t believe how bad it sounded in its new home - pesky room acoustics!
Gary
I think mentioning a graphic Equalizer in a hifi system would have Mr Vereker jumping out of his grave and knocking your teeth in … a quality simple bass treble control can have its place, and you tend to see more in commercial setups on active speakers as opposed to domestic hifi setups… but it is true tone controls simply are not fashionable in domestic hifi setups, and has led to a market of accessories including styles of interconnects that try and achieve the same thing in a less precise way …. Though increasingly you see so called DSP masquerading as tone controls, but as it doesn’t mention the term ‘tone control’ it seems to be more acceptable 
1 and 2…in that order…enjoy…