Pros: great value for the money, slightly warm sounding, leans toward detail and clarity, handles treble really well, great wide soundstage
Cons: build quality, may run into some restrictions when looking to tube roll, picks up mobile interference, gets really hot
Little Dot the title can be telling in many different ways - I read one head-fier refer it as a small and unimportant smear (when comparing to the Darkvoice). But in this case the Little would be how much you'd pay for something, but in return you get more than you could have bargained for. Here's why:
If you've considered to try out tube amps then the LDMKIII could be either a good or not so good start for different reasons. If you're after considerable warmth and alteration of sound toward the darker side then the LDMKIII can supply you with that, but only to some extent - this amplifier is not all about warmth but also detail. If you're going from a transparent or clinical sounding amplifier then you'll definately hear the difference. It certainly makes the mids more smooth and the bass hit just slightly deeper. But rather than smoke and fire - I would define its warmth as cozy ember, it's not overly aggresive and alterating, but you feel its presence; and in a good way. However, it is not only nice in the midrange it extends and smoothes the treble a little bit. If you've decided to pair the DT990 with the LDMKIII then definately look into tube rolling (stock tubes rarely sound good in any case). With the Voskhod tubes it made the highs on the DT990 slightly more bearable in that they felt smoother, while they were considerably less promiment with the Mullard M8100. At the moment I have my HD650s paired with the LDMKIII and the Audio-gd NFB-3 (all of which are considered to be 'warm') and still what I feel I get most out of the LDMKIII in the system is detail - you could almost say its leaning toward the transparent side for being a tube amplifier - even with the warm tubes like M8100. Whatever I listen to the bass is never muddy or bloated, and the mids are not smeared in any way - there is considerable clarity and detail, and some of it is thanks to the treble extension. Its 'warmth' is not overpowering... it's there, as a companion to the clear detail and soundstage that this device furnaces. And if that is what you want from your amplifier then the Little Dot is a great choice. However, I have read that compared to some other tube amps in its price range it has less tube rolling options (might have changed in the years), nontheless you have options and quite a few of them - all offering different things and not just slight differences.
For me it's hard to comment on the design - I generally liked it and prefered it to other tube amps. But it might not rock everyone's boat (it shares similar shape as the other post MKII products, ie the half-cylindrical shape).
Build quality can be argued over as well. I've read that some people had some faulty ones shipped to them. In my case I haven't had much trouble except that the back AC connect is a little loose (not that it's on the verge of falling off because it won't, it's just not entirely 'plastered' there, you know) it's not something that is an error in just my device but a general build issue - no biggie. Other than that the tubes run very hot - speaking of the power tubes that can run to 120 degrees according to the user's manual. And in turn the entire device runs quite warm - even the case is fairly warm to touch. I don't see its heat problem as a big issue unless you live in a really hot place and have little ventilation. Tubes do run hot in general, but for its size I would think that the LDMKIII is a tad warmer than it should be. Lastly, some have reported that they have heard interference noise that the Little Dot picked up from their phones. I had only one case of this happening to me and it was just slight and quite brief (mobile phone in pocket) - but it actually happening does prove true to others' finding and perhaps not something you would find ideal in an amplifier, even if it's budget oriented.
Generally I would recommend this amplifier on the condition that you change the tubes for something more approriate and better sounding. And again, the sound on this device is pleasent sounding and full of detail. It might even bring out flaws in your source - cause it did in some of my tracks which unfortunately are around 192kbps and 128kbps until I buy and rip the CD quality of just these hard-to-get tracks. With my FLAC files on 900-1200kpbs the LDMKIII really brings out a new layer of sound without any terrible distortion. And while it brings warmth to the table it's not necessarily dark, deep and powerful, but smooth, sweet and mellow - which I think complements the HD650 well if you feel that you could use just a little bit more warmer tones to your tunes.
Also note that some users have found distinct differences in sound signature when switching between the gain setting on this device. To my personal liking I prefer the gain 10x and 5x over the 4x and 3x. But depending on your taste it might be different - it just requires experimenting, just like the tubes.
I've run both Beyerdynamic DT990 600ohm and Sennheiser HD650 through the Little Dot MKIII and found it to work well with both - of course with different tubes to alter the sound in different ways.