I think the designer (Superdad?) would say something like: The LPS-1 is definitely 100% immune to its feeder p/s because the super caps bank is completely disconnected from its input at the point it is active. And that therefore the only possible other impact could be the noise that the feeder p/s sends back to the mains circuit. I can't confirm or deny that, but my feeder p/s is the iFi 9v, which I find slightly more convenient to use than the Meanwell, but I haven't tried to SQ compare them feeding an LPS-1.
Anyway, I've done some more comparisons now that I've re-established a reference point in my new location, with some interesting results:
Having confimed that Laptop USB socket -> Anker USB/ethernet dongle -> ethernet -> mR v1.3 -> USB -> DAC is further improved by inserting an IR after the mR, my next step was to remove the mR to see if USB direct, cleaned up by IR, could rival the more complicated ethernet path. For this test, the IR was powered by the LPS-1 to give it the best chance. So I changed my Roon's zone to output to USB via DAVE's ASIO driver.
I was surprised that SQ took a big step downwards. And also much quieter - in the order of 8-10dB, which shouldn't be the case with a digital stream. In case the IR was causing this dB drop, I removed the IR, so now had just a USB cable between laptop and DAC. SQ took a further big downturn, to the point it was quite horrible now - and still too quiet. After a bit more investigation I found that I had left Roon's auto volume leveling feature switched on the USB zone. After I switched off the auto volume levelling, the volume went back to normal and the SQ jumped up again, but not to the same level as my mR starting point.
Going back to my original comparison, it was clear that IR alone was not as good as mR+IR and not even as good as mR alone.
These were quite obvious differences, with the direct USB path sounding more digital-in-a-bad way, managing to combine the worst of all worlds: sounding both rather muffled, flat and dull, and yet rather brittle and edgy. The IR did improve upon having just a USB cable, but it still fell short of the mR. To put this into perspective, my informal subjective scoring, with 10 for my top reference, would go something like:
- mR + IR ...........................................10
- mR .....................................................8
- IR .......................................................4
- USB cable alone ................................1
- USB cable and Roon auto volume ....-2 (minus 2)
To put this into further perspective, a score lower than 6 would have me strongly considering ditching computer audio and going back to my CD player.
And a negative score would have me ditching hifi altogether and just getting some ibuds and be done with it. I was shocked how bad this sounded.
Don't take these scores too literally, it's just a bit of fun to give an indication of my subjective reaction on the day.
My main conclusions from this (admittedly very brief) comparison are:
- If you have a normal laptop or PC, then a direct USB connection to your DAC is a bad thing to do. Very, very bad. If you disagree, then you either have some black magic going on somewhere, or you haven't yet heard what a proper high end system can achieve.
- An IR can help the direct USB link, but it can't do it successfully enough just on its own.
- Adding an MR can help a lot, and turns yout laptop/PC into at least the start of a high end source.
- Adding an IR after the mR further improves this high end source.
- Roon auto volume levelling (random tracks or albums all play at similar volumes) is a great idea that I'd like to use, but won't whilst the SQ is so degraded (flat and dull).
- I'm still hoping that a suitably tweaked dedicated server will remove the need for all of these little boxes - that's my long term goal
- In the meantime I may just upgrade my mR to V1.4 status (super clock added) to keep me happier whilst looking for the perfect server. I don't want to spend lots of money on a uR or those SOtM tri-thingys becuase I'm still hoping I can drop all these little boxes one day.