The Sbooster instructions call for you to snip one wire that runs from the IEC to the stock power switch, in order to remove the IEC and replace it with the Sbooster connector which mounts in the space now formerly occupied by the old IEC.
By necessity, to reinstall the old power supply, you have to reconnect the wire you snipped, which you’d do by resoldering the tip of the wire back onto the IEC.
The instructions from Sbooster are well detailed on this process.
I thought I should probably feedback on where I ended up here. After a few trials I purchased the now end-of-life Hegel H360. Nobody would accuse it of being compact but it sounds fantastic. Out of curiosity I have made some brief, highly subjective comparisons between the internal DAC and the D2 (balanced). The H360 is at a double disadvantage as my room correction filters are configured for the D2 (not sure if the phasing would be different with the H360 DAC) and it is by default quieter on the input (of course I tried to match the volumes).
For MQA (Roon doing first unfold) there was no comparison - to me the D2 (which of course does the full rendering) sounded significantly better. For straight PCM the jury is still out - the D2 seems to give more detail, more soundstage, better timbre and more instrument separation but to my ears sounds a little ‘bright’ with this amp, leaving the H360 DAC sounding a little more ‘natural’, for what those terms are worth. I haven’t finalised my RC filters yet though, and it’s still pretty early days, so we’ll see how this pans out.
Edit: I’ve now had a chance to do a lot more listening with more careful volume matching. I think my conclusion is that the DAC in the H360 is very good and that both it and the D2 have strengths and weaknesses. The D2 seems unforgiving of brightly produced/mastered tracks and I find these more enjoyable through the H360 - it does a wonderful job with female vocals. On the other hand, I think the D2 gives better soundstaging, instrument separation and detail so I guess it depends on your personal preference/priorities.
I’ve had a number of listening sessions with the Sbooster Linear power supply, which seems to have settled down a bit more from new, so I feel ok about sharing impressions.
I’m a big fan of the upgrade but don’t want to overhype its impact. Generally my initial impressions still hold:
it adds a very firm bass foundation which is not at all slight but quite noticeable. Drums have more weight and impact, and bass guitar has more body.
better soundstage and instrument separation. I can more clearly delineate the finer details of instruments. Guitars seem to leap a bit more from the background. Midrange is wonderful. Vocals have more body and feel more rounded.
more energy and dynamics. The stock D2 is very musical but just ever so laid back. The Sbooster infuses it with more energy, without losing the essential warm tone. A helpful analogy would be a tube amp set on triode, which has a nice presence and very transparent, but can be soft at the extremes, vs ultra linear mode which adds dynamics, firms up bass, and adds a tad of airiness on top. The Sbooster is like triode infused with all the good parts of ultra linear mode.
I like the stock D2 but wanted a bit more dynamics and bass weight and that’s exactly what I got with the Sbooster upgrade.
The comparison is not night and day, and it’s not like the upgrade crushes the stock D2. Rather, I hear a noticeable difference that eliminates any niggles I had with the stock D2, and gives it more life and energy.
I’m a fan of the Sbooster clearly, and can recommend it without reservation. The positives it brings makes up for any trepidation around the installation.
Peter, you mentioned there is no D3. Are there any plans for one or any updates that will go beyond DSD128? Or are those upgrades only in the higher priced models? I’m researching Lumin, Bluesound and others to determine my best upgrade path.
Please consider Lumin T2 (or X1) that supports DSD512.
Thanks for the reply!
Highly recommend the T2, just got it and it sounds fantastic even before break-in.
I’ve been very pleased with my D2 in the year or so that I’ve owned it. I’ve been wondering though, what improvements I might hear if I stepped up to the T2.
Thanks Peter, that’s a very helpful post and link. 
Hi @wklie
any chance that D2 will be replaced with a new model in the near future? What is your recommendation?
I cannot discuss future plans, but please don’t worry about it being replaced anytime soon.
Hi,
I have got a chance to test a demo of Lumin D2 from my local dealer. I really like the general sound, but there was a serious issue for me: I think that the internal power supply makes a high-pitched noise, „electronic” noise, coil whine which was audible and unpleasant. Well, the dealer didn’t hear it of course, but for me it was audible even from 2 m distance. Well, I was looking forward to D2 … I have returned the demo model to the dealer. What about yours D2… Are they „dead silent” in standby mode?
They have another D2 in stock, not opened, factory sealed, so I was not allowed to test it.
Don’t hear anything on mine.
But then again I’m not the youngest anymore.
Certainly the first time I’m hearing anyone mention this issue.
We consider coil whine to be abnormal. Please be assured that having coil whine is definitely not representative of Lumin products. Any unit that exhibits a coil whine needs to be repaired.
It is normal that some people can hear coil whine, some people cannot.
Thanks. I will somehow persuade the dealer to let me listen to the second unit.
Please kindly inform the dealer we will repair his demo unit (through the distributor usually).
If you purchase a Lumin and in the unlikely event that the unit has any defect, we will help make sure you get a replacement.
@sojer2005 - no sound from my D2 either (which is more than can be said for the amp next to it). FWIW, I tend to be pretty sensitive to that sort of noise.
What happens to your amp? Transformer hum?
Yes, I believe so - it’s a Hegel H360 - I may try a DC blocker sometime but they seem expensive for something that, as I understand it, shouldn’t affect the audio…thoughts welcome though.