Firstly, your headphones. I have a pair of Grado 225x. They are superb but, as
@WayneKerr says, very revealing. My Cyrus amp has a very good headphone output, but the Grados would benefit from a better separate headphone amp.
No to the overall system. The Denon is virtually the same as the Marantz MCR-612, and both are very capable units considering how much is packed into one small box at such an affordable price. One of these with a good pair of affordable speakers will offer a lot of enjoyment and flexibility. Would it compare with the sound of a set-up like the one I'm using (all fairly affordable kit)? No.
What is the setup you're using?
Also be aware that HEOS is simply Denon and Marantz's take on multi-room, and to utilise it you would need HEOS-capable Denon or Marantz equipment in the other rooms.
This has been a small concern. Questions in my mind are "what if they stop support in the future" and "if I'm looking at multi-room, should I also consider Sonos"
Put one of these amps with the CXN and a CXC transport (if you want CD playback) and you've got very capable electronics which could comfortably drive quite a wide range of speakers. Do you want stand mounted speakers, or floorstanders?
CD player is a must (partly because I want my son to have that tactile experience with music that I did - looking at artwork, reading the lyrics and notes in the booklets etc. It was a huge part of enjoying music to me when I was younger)
I'm open on speakers.
If you want to go the separates route and have an easy solution, the Cambridge set-up is a great way to go, however if you want to spend some time trying a good range of things I would recommend doing so. There's plenty of sub-£1k amps to choose from, some of which include streaming functionality and some you would need to use with an external streamer, but there are separate streaming solutions which are much cheaper than the CXN and every bit as capable.
I'd love to really get into testing, my issue really is it's hard to do so now. My local Richer Sounds are a friendly team but it's a small store with limited stock. The only other audio store in my town is really high end stuff, like speakers starting at £4k and going close to £200k. I'd love to do what I do with guitars and visit the shop and spend hours playing different ones, comparing, and seeing what feels right. That's what I did with the headphones.
There just seem to be a dearth of audio shops now - and with speakers, I'm aware that the room itself will have a significant impact and an audio shop's demo room won't be exactly the same as mine.
Let us know some more information... How large is your room? Where will the speakers be positioned? What music do you listen to? Is vinyl on your radar or not? Will streaming be your main source? What model is your current Technics system? What will the split be between headphone use and listening through speakers?
Great questions! I've attached a photo of the room - forgive the mess, my young son has been unwell. I'm standing in the doorway to take this photo. Currently the hifi is in the far left corner in front of the curtain. Speakers are currently on the floor behind the orange chairs.
I'd like to have a speaker each side of us (sat on the sofa) rather than all coming from one side, so I'm thinking the next one will be either on the near left side, which is a TV entertainment cabinet (we'd have to use this space if we got separates), or an all in one like the Denon could sit in the glass table on the near right side. The advantage of being on that glass table is we could have a speaker each end of the sofa and hide the cables behind it. If the equipment is on the left side, I have to get the cable around the chimney breast discreetly.
What music I listen to: primarily rock but I've been listening to a wider variety with the Grados because it's so much more enjoyable with the extra clarity. I also enjoy classical and acoustic stuff. The salesman also played Yosi Horikawa's "Bubbles" to show me how the headphones play music that makes use of the space, and it's made me want to explore different sounds. So, I'd want something capable of Dolly Parton to Hans Zimmer.
Vinyl: no. My wife's mentioned it but I doubt we will get it.
Will streaming be my main source: if the equipment can stream at a quality that's at least equal to CDs, yes, streaming would be the main source with CDs also being required from time to time. If the unit has DAB that would be used occasionally too, but not a deal breaker.
The current Technics is SE-CH570
The split between headphones and speakers: not 100% sure at this stage but probably 60-70% in favour of speakers. We play a lot of music on our phone for our son, and the nice headphones have got me remembering music as entertainment in its own right instead of being background noise, so a good system would definitely inspire us to play it more.