Musical Fidelity's x10-v3 tube output buffer?

My experience of the new X-10v3 is very positive.
I think it is important to note at the outset that the results when used with the X-PSU (power supply) are several levels of excellence higher.
Without the X-PSU, the X-10 came across as sweet and smooth, wonderful for strident or slightly harsh CDs, but perhaps mellowing CDs that needed no such assistance. Female voice and flute seemed to benefit nicely. Transients however lost some bite. Soundstage doesn't seem to be affcted one way or the other.
However, with the X-PSU in place, the X-10 is in a different league altogether. Any "veiling" has vanished and the sound is as detailed as one could wish, but with a sweetness that is beguiling and as good as anything I have heard on CD. Absolutely lovely. and the soundstage really does snap into sharper focus and extends deeper.
As a combination, I would recommend the X-10 and X-PSU very strongly indeed. On it's own, I'm not so enthusiastic.
I have just purchased the X-DAC too. But after just a couple of days, I can't give a definitive opinion yet. Both the unit and the new digital cable need some break-in time. Let me say though, that the X-Ray player I'm using with the above units is a splendid performer in its own right, so any improvement should make it spectacular.

for every system, nor will the X-10 be right for everyone's setup.
It would be beneficial to mention a couple of points.
First, the X-10 v3 does add a 1db signal boost. Having said that, I don't hear any extra noise at all.
Secondly, as I said in my original post, the X-10 v3 performs extremely well with the X-PSU, and not so noticeably well without the PSU. The same with the X-Can headphone amp.
Users might also note some difference (as I did) when using the X-10 v3 between source and pre-amp and, alternatively, between pre and power amp.
Having heard VERY pleasing musical results from the X-10 v3, I think it is worth the effort to audition it to see if it benefits individual systems. It has certainly boosted my listening enjoyment a great deal.
From my experience, I'd say anyone reporting negatively without having heard it with the X-PSU has not done it proper justice. I also suspect that some are reporting here on their experience with the old model, not the newly released and much-better v3 version.

When using the tube buffer, you enter a situation where your interconnects need to be considered. For example, many tube users use relatively bright-sounding interconnects to give some sparkle to the extra warmth of tube sound.
It figures then (generalizing for a moment of course), that those using warmer-sounding interconnects that sound great with their non-tube gear, might perceive a "deficiency" when using the tube buffer in the same setup.
The tube buffer benefits from being integrated into a system, not just thrown in and judged without due consideration to interconnects etc.
If an expensive system is already assembled, the benefits of the tube buffer are unlikely to justify many hundreds of dollars of interconnect changes, BUT, when building a new system from scratch and selecting all ancilliary items with the tube buffer in place, I suspect most users will be delighted with the results.