I bought one of these about two months ago and have been meaning to post a review on it, but never had the time to lately. I'll try to summarize what I feel about it here...for me it's been a positive addition to my system without a doubt.
The original reason I considered the X10 V3 was for my very modest speaker system built around just the simple Swan M200 computer bookshelf speakers, which is what I mostly use nowdays for music. I felt they were just a little edgy in the treble and was hoping to curb that a bit. They also just sounded a little flat and lifeless, and didn't have much soundstage depth to them. The other thing I had wondered over was considering that my source isn't exactly a slouch (Arcam FMJ CD23T), if adding the X10 could potentially degrade the sound rather than improve it at all. It came down to either trying the X10 or considering a new seperate source for the speakers, which would've been the more costly option. I chose to try the X10 first.
The next thing I had to consider was interconnects...by adding the X10 in, I would have to get another pair of pricey interconnects, as I suspected the interconnects would matter. And as I had anticipated, they indeed made a noticeable impact to the sound, particularly the pair running between the X10 and the speakers. I finally settled for a pair of Luminous Audio Synchestra References for the source to X10, and used my old standby Zcable Live V5 for the X10 to speakers.
Settling back for the listen didn't reveal any major tonal differences that I was expecting of tubes, and that impressions remained. The treble didn't suddenly get softer, the midrange didn't suddenly get more syrupy or warmer. What did change though was the bass...the M200s are not very good at deep bass to begin with, but adding in the X10 somehow added in additional bass depth. Whereas before some bass notes would get totally lost, I could now faintly hear them trailing off, though not nearly as well as a system that had a sub or better midrange driver.
While tonally there wasn't a lot of changes, there is something more subtle going on where the entire presentation sounds (or feels) just a bit slower, more lazy, and more relaxed. Things sound a little smoother. It's hard to pin down but when you're being surrounded by music in an enclosed space, it's a realization that sort of creeps up on you.
The biggest difference though was in the soundstage...it added considerable depth, in that I suddenly felt like things were playing farther away from me than before. Being that this was also a problem for the M200s, and it was a problem I never thought would ever change, I was very pleasantly surprised at this change, and this alone convinced me the X10 V3 was worth keeping.
While I didn't originally buy it for my headphone system, I did also take it for a spin there, and here I found that the X10 made a bigger tonal impact with pretty much stereotypical tube traits. The treble was slightly softened, midrange a little warmer, and the bass had a slight bit of rounding off at the very bottom end. Not too much happened as far as soundstaging goes though.
All in all, whether the X10 V3 is for you or not is probably going to be up to the rest of your system, as I'd imagine it's highly dependant on what else you mate it with. I wasn't expecting it to do a whole lot for mine being my source isn't bad, but that wasn't the case, and I ended up liking what it did quite a bit. It's certainly not cheap though as an accessory, plus you have to consider additional interconnects.
