I posted a similar post a few weeks ago and based on the input and suggestions, I upgraded my DAC and pre-amp. Since that was so much fun and I’ve been sooooooo very pleased with the result, let’s do it again!
Here’s my current setup:
Streamer: Aurender N10
DAC: Weiss 204
Pre-Amp: Naim NAC282
Power-Amp: Naim NAP200
Power: HiCap
Speakers: Harbeth Bookshelf and stereo pair of Rel Subwoofers
What’s my next upgrade? Let the games begin and thanks in advance for your input!
Did you upgrade your streamer too? Bluesound to Aurender? I can’t keep up 
I’m gonna say NAP 250 to match your 282. Seems the logical next step to me!
Good books, art, something to drink?
What rack do you use?
Cables?
I would calm down and enjoy your new updates first and when you get over this initial excitement/impression and start the process of actually living with it you can consider what if anything your system lacks.
That process will inform you what would help the system further.
Yes! I’m struggling to catch up too! Lol!
Nap300dr if you have the space for it, the prices are so good second hand.
Failing that 250dr
Currently my Harbeth bookshelf speakers are placed within a built-in bookshelf. How much improvement would it make to put them on stands?
That’s good advice. I’ve been so thrilled with the improvement to my system that I’m a bit overexcited. Lol! I can’t help but wonder how much better it can sound - within reason of course. 
I was going to say similar to Chalshus and Robinho - buy more music. Relax, enjoy what you have. But maybe you need to finish this round off in some way, and forum/Naim lore would suggest to me that the NAP250 would certainly be worth a listen with your current system. Then stop, take stock, keep your wallet in a drawer, and appreciate the superb system you have. Good luck anyway, enjoy whatever you decide to do, this stuff is all a total luxury and should be appreciated as such
I don’t know harbeth speakers at all, but generally small speakers sound better on heavy stands…. Any Harbeth aficionados?
I suspect a decent difference. Borrow some and give it a try.
Bookshelf speakers are mostly ill-named and the majority will be improved quite a lot by being put on stand mounts that are suitable for them. If you can get some to try at home that would be best.
I’m not familiar with most of your gear except maybe your speaker. P3ESR is it?
But I bet the forum trend will go for the nap upgrade like already mentioned.
Personally I’m into streaming so I went for a English Electric8 Switch and EE1 for my lastest upgrade, without real expectations. I did a, not serious quick crash installation, just to see if I could hear a difference. The impact was so big I was literally stunt and caught off gard. I had no time during Christmas to look at it seriously so I took it off to come back later and do real set up and sound comparison.
Of course even when my testing will be done it won’t help you either I like it or not, but do not underestimate any components in the audio chain.
(Hopefully I’m not starting a debate here. It’s not my point) 
System all looks very good indeed. 250DR would be my move or 300DR. Depends on your speakers and bass control.
But if what you have is good enough rest there.
I don’t know the streamer at all, so will have to bow to others. However, we have done a fair bit of box-swapping.
The 282 and above are all great preamps. 250 (olive, DR or NC) are great power amps too, and some have said they prefer the new NC250 to a 300DR.
However, we found that an 82 (very like a 282) worked brilliantly with a 250 (and much better than, say, a Nova), but the 300DR seemed hardly better than my old 250 when using the 82.
With a 52 (like a 252) or 552, the 300DR was a lot better than a 250 imho.
Given all that, I would agree with many here and say a 250 is likely to be a meaningful upgrade and the right choice. I wouldn’t get a 300DR for an 282 even though it is what I use (with joy) in Wimbledon. Here in Tassie I am using olive 82/HC/250 and it is a great combo.
I would also say that not all 250s are the same. Other threads will give more on this, but I found the first post-olive 250 quieter but otherwise no better (and possibly worse) than the earlier versions. The DR version fixed that and is well worth paying up for versus the OC “250.2” version it replaced.
YMMV or course. Others here are certainly happy with 282/300DR, esp if they have demanding speakers.
I agree with Chalshus, who is curious about your rack, if any. If you don’t mention it, I suspect you don’t have one or realize the huge difference a good rack can make, as it up grades everything, including your future acquisitions. You don’t have to have a turntable to get a cost-effective benefit from a rack.
Your next upgrade is a quality power supply & DC cable for your Weiss DAC204.
In a bookshelf surrounded bybooks, records, CDs, etc creating a near flush front surface can have beneficial effects, though the shelf should be very solid, to ensure it is vibration-free. Whether stands and moving out into room would improve is something you’d have to try for yourself. You haven’t actually given much info about your speakers at all - I don’t think Harbeth actually list any bookshelf speakers, however they have quite a range of speakers, many of which could be placed on a bookshelf of suitable dimensions and strength… Depending what your speakers actually are, and how widely you auditioned before buying, it might be that you’d get a more substantial improvement than any other change by changing the speakers for something better…
I think a 250DR is the most sensible choice. I had a 282/HC/250-2. It’s a fantastic combination. I later serviced and upgraded everything to HCDR/250DR. Even better.