Penchum has been a long supporter of Little-Tube's products. One thing I have to give him is his long winded yet very satisfying review. Now it is my turn to give something back to this excellent Head-Fi Poster.
Welcome to the world of the Chinese Audiophile.
The Little Dot MKI+ is the latest addition of my collection of amps and headphones. That said, this is actually my second purchase of this amp since the first one was sold to a friend who actually enjoys the audio output of this amplifier so I sold it to him and purchase a second brand new model. This time however I am going to give a full review of this portable successor to the headphone amplifier world.
The Americans make excellent units except their prices are rather steep. I still own yet not list on my page the Diablo by LaRocco Audio. I purchased that unit off of ebay due to the price that was listed and nothing more. Luckily for me, I managed to pay less than what they were listed for when brand new. Thank goodness for that.
The latest offering of the Little Dot MK series is labeled MKI+. Features two discrete power supplies, which consists of two 3.7V battery packs that are individually wired to each dedicated OPAMP provided by National Semiconductor. Here is the Short description of the amp provided by Little-Tube
Little Dot MK I+ Portable Headphone Amplifier
The successor to the Little Dot MK I, the new Little Dot MK I+ takes advantage of American National Semiconductor’s newest offerings in ultra-low distortion circuit components: LME49710HA high fidelity operational amplifier and the LME40600TS high performance current buffer. The new power supply consists of two 3.7V 700mA/h Lithium-Ion battery to provide up to 30 hours of high current, ultra-low distortion power to your headphones. Circuit stability and reliability over the previous Little Dot MK I has been markedly improved as well. The Little Dot MK I+ also has exceptional compatibility with a wide variety of IEMs, earphones, and full-sized headphones due to its user-selectable three gain settings, as well as output current control via internal jumpers. When jumper caps are set in place, output current increases by 80%, dramatically improving dynamics, impact, and low frequency response with the trade-off of lower battery life.
Little Dot MK I+ Technical Specifications:
* Line Input: 3.5mm (1/8 inch) mini-stereo
* Headphone Output: 3.5mm (1/8 inch) mini-stereo
* Frequency Response: 5 Hz (-0.6dB) to 200KHz (-0.3db)
* THD+N: 0.0010% (1V @ 1000 Hz)
* Suitable Headphone Impedance: 8 - 300 ohms
* Input Impedance: 20K ohms
* Power Output: 200mW (32 ohms)
* Gain Factor: 1, 2, 4x (User Selectable)
* Battery Life: up to 30 hours per charge
* Battery Overcharge Protection
* Universal Voltage AC Charger/Adapter included (Type B plug)
* Measurements:
* Metric: 95 mm (length) by 70 mm (width) by 24 mm (height)
* English: 3.74 inches (length) by 2.75 inches (width) by 0.94 inches (height)
* Weight: 192 g (includes internal battery)
* 1 Year Little Dot Warranty
This is something short of a great thing in comparison to the original MKI. The MKI used a DIP socket to allow for op-amp rolling. What this means for us crazy audiophiles is that we can change the op-amp on a whim so that we can further improve the sound quality. Penchum made a good recommendation with the MKI by changing the op-amp from the stock chip to Linear technologies offering, which is the LT1364. This change softened the blow with the overall upper frequency and tightened the lower frequency range. The mid-range remain neutral while increasing battery life by about ten percent based on my last run of the amp compared to the original op-amp chip installed.
The new amp features two dedicated op-amps which is then supplied by two dedicated wired 3.7V lithium-polymer battery packs at 700-MaH each. A different power supply is provided to power and charge the amp. 9.6VDC is the supply voltage to charge and sustain the amp for desktop operation. Some portable amps have a tendency to change the sonic quality by operating at a slightly higher voltage then in the standard operating voltage range of a battery. This is no such case with this portable amp. The sonic character of this amp coupled to the AKG K701 with the mod that I performed has a better reinforcement of upper, mid, and low frequency range without being overly harsh. The two jumper points are for current drive increases and by bridging each one (one jumper per channel and per op-amp/buffer) of them, the output drive increases quite a bit. I wouldn't say eighty percent, however all I can say is that it drives the K701 better than with the MKI by a factor of two.
I have already tried the bridging of the jumpers to increase the current drive with the K701, however I prefer the longevity of the possible 30-hours the amp may provide rather than the short ten that I managed to squeeze out of the amp during my two tests conducted on the amp (The second purchased unit is currently being burned-in as we speak).
The LME49710HA operational amplifier was evidently designed for use with audio applications. According to the website, the op-amp was designed with idea of high-end audio applications especially since the company noticed that many of their operational amplifiers are being used by Chinese audio companies to improve or aid in excellent sonic qualities that many American and European manufacturers have with their higher-end priced amplifiers. I wasn't a big fan of Chinese amp manufacturers until I encountered the Little Dot Micro+. The amp was one of the longest operating and very decent sounding despite the numerous posts citing that the sound was very thin. Thin would not be the word I would choose to describe the sonic quality, however something close to lacking would be a better word. The overall sonic quality of the Little Dot Micro+ was better than directly from the audio source itself. Amplifiers are designed to amp up an audio source signal to best possible strength before distortion sets in. The LDM+ is what suppose to do in any given situation.
The LDMKI+ is an excellent amplifier in many regards. The power amplification of 200-mW at 32-ohms is rather low, however the current drive specs are not shown unless you have something to test that output. Surprisingly I had a friend measure the continuous current drive output of 300-MaH, which means that there is more than enough current drive to provide for a very wide range of headphones. There is also a full 3-volt swing provided to any headphone that would need that kind of voltage drive. Combine those numbers of voltage, current, power drive and that would make an excellent choice for many headphone enthusiasts.
Using the first amp as the basis for this review, I will break it down in hourly sections.
0 to 30-hours
After opening the amp up, the first I did was bring the amp to a full charge overnight. Once charged, I began to put the amp through its paces. First off using Telarc's release of the 1812 Overture conducted by Erich Kunzel released in 2000 DSD. This particular release contains about seven tracks starting off with the 1812 Overture and ending with the Mazeppa - Cossack Dance. Running the CD on repeat for the next thirty hours giving an occasional listening test to determine if any changes in sonic character were detected. I must report that from 0-hour to hour ten, there was already a detectable change. It was toward the better in every regard.
During the first ten hours of burn-in, the overall character of the way the amp handled the tracks were less than subtle. Meaning that the treble was rather harsh to almost unbearable. The mid range had a certain metallic klang per say. The bass frequencies were the only plus I can say with this amplifier at the time. The AKG K701 is considered to be a Reference Class headphone, however their definition of reference is clear, detailed, and clean audio quality with the original representation of sound stage. Unfortunately there is a quality about the K701 that has been a problem plaguing that particular model. Most frequencies above 7-KHz begins a sonic quality that comes close to bright, brittle, and overly aggressive. With an amplifier that can be rather aggressive coupled to an overly aggressive headphone, some would say that this would make a very bad combination. That isn't always the case especially when a person like myself spends the time testing modifications to make the audio signature of an aggressive and harsh headphone more neutral.
31 to 60-hour mark
After carefully listening in the less than 30-hour mark, the audio character was not something I wanted to say that I liked, however I bought the amp in good faith, so I decided to give it a try. The Sennheiser HD650 would be a better fit with this amp, however I decided to put the older LDMKI for use with the HD650, while the MKI+ for use with the K701 by AKG. Now well into the 40-hour mark, the amp is beginning to make the K701 shine. The Sound stage was beginning to open up while presenting details that make the K701 a class in its own. The Sennheiser HD650 was connected to the LDMKI+ for a short time to test the audio quality of the amp and surprisingly the results were much better than I figured out to be. The sound stage is very open with a level of sophistication that I never ever heard of when I had the HD650 connected to the LDMKI (before the LT1364 upgrade).
Dynamic passages with the MKI+ is much more pronounce than with the older MKI (again before the LT1364 upgrade - after the upgrade, the MKI is very much close to the audio signature of the MKI+). So I decided to change the music a little bit to test both the sound stage and dynamic range of the amp since the representation of the sound stage is what the amp if suppose to reproduce. Sounds like mumbo jumbo, and it isn't because of the time change between the USA and Germany, I think I am starting to get a little wary. Anyhow the LDMKI+ is one amp that can seriously pack a dynamic punch when needed to or demanded of depending on the audio tracks that is.
The new CD placed into the tray is Secret Island by Stanley Thomas Keiser. Clarity Recordings is the company that recorded the CD. Citing that they were using twin microphone setup rather than the traditional single placement microphone. Again using the K701 as the point of reference, the sound stage was ever so pronounce with no hint of aggression and harshness. The sonic character has changed from being bright and brittle to warm and tender. The reason I say this is that the K701 headphone is one item that normally is very harsh and brittle to a person's ears, however with one simple mod and the right amplifier, this combination can be the best thing for a person's audiophile experience.
Listening to track two of the Secret Island, the combination of the K701 and the LDMKI+ makes for one sacred marriage. Smooth frequency rolloff coupled to excellent dynamics is something not many would characterize with the K701. This amplifier makes even the most warmest headphones sound rather neutral. The only other amp that I am aware of in the same league as the LDMKI+ is the LaRocco Diablo. Even that amplifier in terms of the pricing class would be defined as outclassed. In the audio category, the Diablo is pretty much on par with the Little Dot MKI+. Again the basis for my reason is my ears. The Diablo would be rather aggressive with the K701 while the LDMKI+ would be rather softer as time goes on. I think that the Diablo has too much power drive thus making for a rather bright sounding amp with an already bright sounding headphone. This is my observation only and not completely shared by the many members of the Head-Fi group.
61 to 100-hours
Switching to vocals now, Jennifer Warnes in the Famous Blue Raincoat. Using this rather old CD labeled by Stereophile as a reference class recording good for testing audio systems is something that I love to use to test both stereo setups and headphone systems. This is the same CD that I used to test the original BE/HE90 Orpheus that I still own to this day. I will not sell the system so don't bother asking.
Her voice and the nasal quality resonates with the same levels as the day it was recorded in that studio many years ago. That is how it sounds and feels with the combination of the K701 and LDMKI+. Compare with the initial stages and now, I will think that now the sound has settled down to the level that would befit the type of amp it is. Oh I forgot to mention that now the amp is connected to AC power to both charge and sustain. The first and second battery charge lasted about 32 and 35-hours respectively. That is more than what was specified by Little-Tube. No matter.
The mid range was very smooth followed by warm mid to low overtones. The Treble was very delicate yet full with no coloration in the tones themselves. This is what a good audiophile headphone setup is suppose to be. Most headphones have a certain amount of coloration to them especially when listening to vocals since these are the things in life that add or remove from the overall listening experience. No such artifacts are heard from with this combination. None either with the other amps as it should be. The K701 settles well with the LDMKI+. The C&C XO+ and Box+ didn't quite settle quickly like the what Little Dot has to offer. I think it is the attention to detail and the quality that it exudes that the other Chinese companies are unable to match (I am talking about the portable class only since the Xin Reference is another portable that doesn't have a smooth following).
I will add more to this description. So for now. I hope to keep this thread alive. Pictures will added later today. Until then, have a great weekend. Thanks Penchum for all of the support
The Second Little Dot MKI+
I have given this amp two fresh re-charges and over 120-hours of listening burn-in. The Surprise is that this amp sounds excellent out of the box. Even better now after 120-hours have passed. I think that the first one that I purchased was because I also had a new headphone being burned-in at the time. I have enclosed some stock images from the Little Dot website seeing as I do not have any tools to open this new amp up at this moment in time.
In comparison to the older Little Dot MKI, the new circuit is much cleaner and well designed. The older unit is a very well designed and built amp, however there is always room for improvement, especially in the world of Audio. I understand that it is not as noticeable, however you will all see that there are two pairs of wires coming from the battery pack. There are two 3.7-volt batteries wrap together to form a single package. One pair wired directly to one set of buffer and op-amp per channel. It has been arranged as though the Left and Right are powered through discrete power supplies thus eliminating a split voltage rail. The LDMKI arrangement uses 4x3.7V power packs wired in series to deliver the voltage required to power both the pre-amp op-amp and the TI headphone amp output stage circuit.
This is how I figured out the sound quality of the LDMKI. However somehow along the line, noise was being introduced when an audio signal is being pass through the volume pot while it being adjusted. Discounting the occasional noise within changes in the volume pot, the Little Dot MKI is an excellent portable and desktop amplifier for the advanced level audiophile. Using a DIP socket type op-amp for use as a pre-amplifier circuit and then using a Texas Instruments 6120 amplifier circuit to provide output current, power, and voltage drive to the given headphone connected. However unlike with the MKI, the MKI+ loses its drive once the headphone impedance increases beyond 300-ohms. I have actually got a chance to test the LDMKI's 600-ohm drive capability and to my surprise, it does very well, however I can't say the same with the MKI+. That doesn't bother me since the test headphone that I used for the 600-ohm experiment was not mine to begin with, so it has little effect on me per say.
The audio output of the LDMKI+ is how I would say much more robust than with the MKI by a margin of 20-percent range. The reason I say this is because of the fact the LDMKI uses a voltage rail that splits the difference of 7.4V per rail. And to give the LDMKI the 600-ohm drive capability, the full voltage swing of the output drive is 6-volts (3+/3- measured by an independent source using an AKG K701 wired to a power meter). Now I do not know what this really means however my ears can hear the difference between the old and the new headphone amp.
The new amp is much more open with dynamic passages such as the Delos Recording of Rite of Spring, Hovhaness "The Volcano", James Horner's Titanic, and naturally "the 1812 Overture" DSD conducted by Erich Kunzel. The LDMKI is very good overall in maintaining the warmth and clarity while keeping the sound stage intact, however give the amp an exceptionally fast and dynamic passage (before the LT1364 upgrade), the amp runs out of breath in a rather subtle manner by conveying its audio out to the headphone as though the listener moved from the sixth row to maybe twenty back and forward to the sixth again. Sounds a little weird, however that happens to be the case with the older versus the newer and better designed voltage drive circuit. Let your ears be the judge of which is better. LDMKI or LDMKI+. However with the LDMKI, once the recommended LT1364 from Linear Technologies op-amp replaces the stock LM4562 (by National Semiconductor) then it is extremely close to the sound of the LDMKI+ in sound stage, dynamics, and sonic character while still adding a certain level of warmth that is not quite featured with the newer LDMKI+.
This is not saying much at all since I quite like the LDMKI and MKI+. Closed headphones are the best in measuring these changes since the listener is isolated from the environment that they are in. This is based on my observations however and not other independent source. Using my more than 12000-hours old Sennheiser HD280-professional for use with a full A/B amp comparison, the LDMKI is only a few steps away from the MKI+. Sonic character, sound stage, and dynamics are very close together. The open sound stage that I heard in the MKI+ is also very much present in the LDMKI. Bass extension between the two amps are exceptionally close, in fact so close, it would require a blind test to tell the difference between the two or a new, not fully burned-in headphone to really tell the difference.
This is based on my hearing observation and not the ramblings of a Chinese helping other Chinese with their products. The C&C XO+ is another amp that can surpass the Little Dot MKI/MKI+ in dynamics, however in other regards, the C&C series amplifiers generally lean toward the brighter side, however coupled to a warmth sounding headphone such as the Sennheiser HD650, the certain warm character of these headphones are somewhat reduced.
Conclusion
Like with almost all of the posts that I have made, this one is going to get buried. It seems that we Junior Head-fi members are not treated with the same level of respect as the ones that posts hundreds of comments every year. Time is used for work, play, and hobbies such as headphones, audiophile listening experiences, and for me cycling.
The Little Dot MKI+ is an excellent headphone amp for those who are not wanting to spend the large sums of cash for one for both home and on the road use. Plugging in the power adapter does not change the sound character of the amp to headphones like some amps do because of the voltage supply change. Sound stage is open with virtually no hint in coloration or change from the original recording. Bass Extension is excellent with a good reinforcement and smooth roll into mid-range and then to high-frequencies. For less than $200.00 USD shipped in the United States is excellent money for a well built amplifier.
The Xin Reference is a great amp, however I do find that their amps built in a rather flimsy like manner. It looks like it's going to break into many pieces. Plus their tech-support is rather thin, which when you contact the members of Little Tube, they generally responds within 48-hours. Now that is technical support. I have had no problems with the amp to require me repairing the amp. Although it would seem that the battery in the Little Dot MKI will need to be replaced due to old age. Hopefully with today's battery chemistry that the batteries will be more stable as they begin to age. This is something that i hope for since I now currently have the latest Apple notebook with the eight hour battery. If this was a computer forum, I would tell those who don't think that the Macbook Pro 17-inch unibody can last that long. They way that i use it, I managed 9:15-hours of usage while still having about 5% battery left. That is a long battery life capacity.
I hope that this review will help those who think that by spending a large sum of money will mean that you will get a great amp. This is always not the case. Spending large sums of money on an amp is downright dumb without first considering what a listener is looking for. I have done that in the first initial stages of headphone audiophile listening. Then I started to sample what China had to offer, and then I came to a realization. The Little Dot series is what changed my perspective. I still have one high-end American made amplifier during the days of spending too much money on audio equipment. Now after acquiring the Sennheiser HD800 (I will return in July to open my new headphone for now I must wait), I now have an amp specifically for the its intended purpose, which is the C&C XO+. The Little Dot MKI/MKI+ for the AKG K701, the C&C Box+ for the HD650, and the C&C XO+ for the Sennheiser HD800. I think that this would make the best combinations for the intended headphones. Each one has a character that will best suit for their intended applications.
The last portable headphone amp that I will probably designate as A/B comparison and a reference point amp is the LaRocco Diablo. In all things fair, the Little Dot MKI/MKI+ are excellent amps for almost all types of low and high-impedance headphones. This is my opinion.
Thanks for reading this review and I hope that this thread stays alive longer than the other ones that I have started. Have a great month ladies and gentlemen. Take care and good health.
Welcome to the world of the Chinese Audiophile.
The Little Dot MKI+ is the latest addition of my collection of amps and headphones. That said, this is actually my second purchase of this amp since the first one was sold to a friend who actually enjoys the audio output of this amplifier so I sold it to him and purchase a second brand new model. This time however I am going to give a full review of this portable successor to the headphone amplifier world.
The Americans make excellent units except their prices are rather steep. I still own yet not list on my page the Diablo by LaRocco Audio. I purchased that unit off of ebay due to the price that was listed and nothing more. Luckily for me, I managed to pay less than what they were listed for when brand new. Thank goodness for that.
The latest offering of the Little Dot MK series is labeled MKI+. Features two discrete power supplies, which consists of two 3.7V battery packs that are individually wired to each dedicated OPAMP provided by National Semiconductor. Here is the Short description of the amp provided by Little-Tube
Little Dot MK I+ Portable Headphone Amplifier
The successor to the Little Dot MK I, the new Little Dot MK I+ takes advantage of American National Semiconductor’s newest offerings in ultra-low distortion circuit components: LME49710HA high fidelity operational amplifier and the LME40600TS high performance current buffer. The new power supply consists of two 3.7V 700mA/h Lithium-Ion battery to provide up to 30 hours of high current, ultra-low distortion power to your headphones. Circuit stability and reliability over the previous Little Dot MK I has been markedly improved as well. The Little Dot MK I+ also has exceptional compatibility with a wide variety of IEMs, earphones, and full-sized headphones due to its user-selectable three gain settings, as well as output current control via internal jumpers. When jumper caps are set in place, output current increases by 80%, dramatically improving dynamics, impact, and low frequency response with the trade-off of lower battery life.
Little Dot MK I+ Technical Specifications:
* Line Input: 3.5mm (1/8 inch) mini-stereo
* Headphone Output: 3.5mm (1/8 inch) mini-stereo
* Frequency Response: 5 Hz (-0.6dB) to 200KHz (-0.3db)
* THD+N: 0.0010% (1V @ 1000 Hz)
* Suitable Headphone Impedance: 8 - 300 ohms
* Input Impedance: 20K ohms
* Power Output: 200mW (32 ohms)
* Gain Factor: 1, 2, 4x (User Selectable)
* Battery Life: up to 30 hours per charge
* Battery Overcharge Protection
* Universal Voltage AC Charger/Adapter included (Type B plug)
* Measurements:
* Metric: 95 mm (length) by 70 mm (width) by 24 mm (height)
* English: 3.74 inches (length) by 2.75 inches (width) by 0.94 inches (height)
* Weight: 192 g (includes internal battery)
* 1 Year Little Dot Warranty
This is something short of a great thing in comparison to the original MKI. The MKI used a DIP socket to allow for op-amp rolling. What this means for us crazy audiophiles is that we can change the op-amp on a whim so that we can further improve the sound quality. Penchum made a good recommendation with the MKI by changing the op-amp from the stock chip to Linear technologies offering, which is the LT1364. This change softened the blow with the overall upper frequency and tightened the lower frequency range. The mid-range remain neutral while increasing battery life by about ten percent based on my last run of the amp compared to the original op-amp chip installed.
The new amp features two dedicated op-amps which is then supplied by two dedicated wired 3.7V lithium-polymer battery packs at 700-MaH each. A different power supply is provided to power and charge the amp. 9.6VDC is the supply voltage to charge and sustain the amp for desktop operation. Some portable amps have a tendency to change the sonic quality by operating at a slightly higher voltage then in the standard operating voltage range of a battery. This is no such case with this portable amp. The sonic character of this amp coupled to the AKG K701 with the mod that I performed has a better reinforcement of upper, mid, and low frequency range without being overly harsh. The two jumper points are for current drive increases and by bridging each one (one jumper per channel and per op-amp/buffer) of them, the output drive increases quite a bit. I wouldn't say eighty percent, however all I can say is that it drives the K701 better than with the MKI by a factor of two.
I have already tried the bridging of the jumpers to increase the current drive with the K701, however I prefer the longevity of the possible 30-hours the amp may provide rather than the short ten that I managed to squeeze out of the amp during my two tests conducted on the amp (The second purchased unit is currently being burned-in as we speak).
The LME49710HA operational amplifier was evidently designed for use with audio applications. According to the website, the op-amp was designed with idea of high-end audio applications especially since the company noticed that many of their operational amplifiers are being used by Chinese audio companies to improve or aid in excellent sonic qualities that many American and European manufacturers have with their higher-end priced amplifiers. I wasn't a big fan of Chinese amp manufacturers until I encountered the Little Dot Micro+. The amp was one of the longest operating and very decent sounding despite the numerous posts citing that the sound was very thin. Thin would not be the word I would choose to describe the sonic quality, however something close to lacking would be a better word. The overall sonic quality of the Little Dot Micro+ was better than directly from the audio source itself. Amplifiers are designed to amp up an audio source signal to best possible strength before distortion sets in. The LDM+ is what suppose to do in any given situation.
The LDMKI+ is an excellent amplifier in many regards. The power amplification of 200-mW at 32-ohms is rather low, however the current drive specs are not shown unless you have something to test that output. Surprisingly I had a friend measure the continuous current drive output of 300-MaH, which means that there is more than enough current drive to provide for a very wide range of headphones. There is also a full 3-volt swing provided to any headphone that would need that kind of voltage drive. Combine those numbers of voltage, current, power drive and that would make an excellent choice for many headphone enthusiasts.
Using the first amp as the basis for this review, I will break it down in hourly sections.
0 to 30-hours
After opening the amp up, the first I did was bring the amp to a full charge overnight. Once charged, I began to put the amp through its paces. First off using Telarc's release of the 1812 Overture conducted by Erich Kunzel released in 2000 DSD. This particular release contains about seven tracks starting off with the 1812 Overture and ending with the Mazeppa - Cossack Dance. Running the CD on repeat for the next thirty hours giving an occasional listening test to determine if any changes in sonic character were detected. I must report that from 0-hour to hour ten, there was already a detectable change. It was toward the better in every regard.
During the first ten hours of burn-in, the overall character of the way the amp handled the tracks were less than subtle. Meaning that the treble was rather harsh to almost unbearable. The mid range had a certain metallic klang per say. The bass frequencies were the only plus I can say with this amplifier at the time. The AKG K701 is considered to be a Reference Class headphone, however their definition of reference is clear, detailed, and clean audio quality with the original representation of sound stage. Unfortunately there is a quality about the K701 that has been a problem plaguing that particular model. Most frequencies above 7-KHz begins a sonic quality that comes close to bright, brittle, and overly aggressive. With an amplifier that can be rather aggressive coupled to an overly aggressive headphone, some would say that this would make a very bad combination. That isn't always the case especially when a person like myself spends the time testing modifications to make the audio signature of an aggressive and harsh headphone more neutral.
31 to 60-hour markAfter carefully listening in the less than 30-hour mark, the audio character was not something I wanted to say that I liked, however I bought the amp in good faith, so I decided to give it a try. The Sennheiser HD650 would be a better fit with this amp, however I decided to put the older LDMKI for use with the HD650, while the MKI+ for use with the K701 by AKG. Now well into the 40-hour mark, the amp is beginning to make the K701 shine. The Sound stage was beginning to open up while presenting details that make the K701 a class in its own. The Sennheiser HD650 was connected to the LDMKI+ for a short time to test the audio quality of the amp and surprisingly the results were much better than I figured out to be. The sound stage is very open with a level of sophistication that I never ever heard of when I had the HD650 connected to the LDMKI (before the LT1364 upgrade).
Dynamic passages with the MKI+ is much more pronounce than with the older MKI (again before the LT1364 upgrade - after the upgrade, the MKI is very much close to the audio signature of the MKI+). So I decided to change the music a little bit to test both the sound stage and dynamic range of the amp since the representation of the sound stage is what the amp if suppose to reproduce. Sounds like mumbo jumbo, and it isn't because of the time change between the USA and Germany, I think I am starting to get a little wary. Anyhow the LDMKI+ is one amp that can seriously pack a dynamic punch when needed to or demanded of depending on the audio tracks that is.
The new CD placed into the tray is Secret Island by Stanley Thomas Keiser. Clarity Recordings is the company that recorded the CD. Citing that they were using twin microphone setup rather than the traditional single placement microphone. Again using the K701 as the point of reference, the sound stage was ever so pronounce with no hint of aggression and harshness. The sonic character has changed from being bright and brittle to warm and tender. The reason I say this is that the K701 headphone is one item that normally is very harsh and brittle to a person's ears, however with one simple mod and the right amplifier, this combination can be the best thing for a person's audiophile experience.
Listening to track two of the Secret Island, the combination of the K701 and the LDMKI+ makes for one sacred marriage. Smooth frequency rolloff coupled to excellent dynamics is something not many would characterize with the K701. This amplifier makes even the most warmest headphones sound rather neutral. The only other amp that I am aware of in the same league as the LDMKI+ is the LaRocco Diablo. Even that amplifier in terms of the pricing class would be defined as outclassed. In the audio category, the Diablo is pretty much on par with the Little Dot MKI+. Again the basis for my reason is my ears. The Diablo would be rather aggressive with the K701 while the LDMKI+ would be rather softer as time goes on. I think that the Diablo has too much power drive thus making for a rather bright sounding amp with an already bright sounding headphone. This is my observation only and not completely shared by the many members of the Head-Fi group.
61 to 100-hoursSwitching to vocals now, Jennifer Warnes in the Famous Blue Raincoat. Using this rather old CD labeled by Stereophile as a reference class recording good for testing audio systems is something that I love to use to test both stereo setups and headphone systems. This is the same CD that I used to test the original BE/HE90 Orpheus that I still own to this day. I will not sell the system so don't bother asking.
Her voice and the nasal quality resonates with the same levels as the day it was recorded in that studio many years ago. That is how it sounds and feels with the combination of the K701 and LDMKI+. Compare with the initial stages and now, I will think that now the sound has settled down to the level that would befit the type of amp it is. Oh I forgot to mention that now the amp is connected to AC power to both charge and sustain. The first and second battery charge lasted about 32 and 35-hours respectively. That is more than what was specified by Little-Tube. No matter.
The mid range was very smooth followed by warm mid to low overtones. The Treble was very delicate yet full with no coloration in the tones themselves. This is what a good audiophile headphone setup is suppose to be. Most headphones have a certain amount of coloration to them especially when listening to vocals since these are the things in life that add or remove from the overall listening experience. No such artifacts are heard from with this combination. None either with the other amps as it should be. The K701 settles well with the LDMKI+. The C&C XO+ and Box+ didn't quite settle quickly like the what Little Dot has to offer. I think it is the attention to detail and the quality that it exudes that the other Chinese companies are unable to match (I am talking about the portable class only since the Xin Reference is another portable that doesn't have a smooth following).
I will add more to this description. So for now. I hope to keep this thread alive. Pictures will added later today. Until then, have a great weekend. Thanks Penchum for all of the support
The Second Little Dot MKI+
I have given this amp two fresh re-charges and over 120-hours of listening burn-in. The Surprise is that this amp sounds excellent out of the box. Even better now after 120-hours have passed. I think that the first one that I purchased was because I also had a new headphone being burned-in at the time. I have enclosed some stock images from the Little Dot website seeing as I do not have any tools to open this new amp up at this moment in time.
In comparison to the older Little Dot MKI, the new circuit is much cleaner and well designed. The older unit is a very well designed and built amp, however there is always room for improvement, especially in the world of Audio. I understand that it is not as noticeable, however you will all see that there are two pairs of wires coming from the battery pack. There are two 3.7-volt batteries wrap together to form a single package. One pair wired directly to one set of buffer and op-amp per channel. It has been arranged as though the Left and Right are powered through discrete power supplies thus eliminating a split voltage rail. The LDMKI arrangement uses 4x3.7V power packs wired in series to deliver the voltage required to power both the pre-amp op-amp and the TI headphone amp output stage circuit.
This is how I figured out the sound quality of the LDMKI. However somehow along the line, noise was being introduced when an audio signal is being pass through the volume pot while it being adjusted. Discounting the occasional noise within changes in the volume pot, the Little Dot MKI is an excellent portable and desktop amplifier for the advanced level audiophile. Using a DIP socket type op-amp for use as a pre-amplifier circuit and then using a Texas Instruments 6120 amplifier circuit to provide output current, power, and voltage drive to the given headphone connected. However unlike with the MKI, the MKI+ loses its drive once the headphone impedance increases beyond 300-ohms. I have actually got a chance to test the LDMKI's 600-ohm drive capability and to my surprise, it does very well, however I can't say the same with the MKI+. That doesn't bother me since the test headphone that I used for the 600-ohm experiment was not mine to begin with, so it has little effect on me per say.
The audio output of the LDMKI+ is how I would say much more robust than with the MKI by a margin of 20-percent range. The reason I say this is because of the fact the LDMKI uses a voltage rail that splits the difference of 7.4V per rail. And to give the LDMKI the 600-ohm drive capability, the full voltage swing of the output drive is 6-volts (3+/3- measured by an independent source using an AKG K701 wired to a power meter). Now I do not know what this really means however my ears can hear the difference between the old and the new headphone amp.
The new amp is much more open with dynamic passages such as the Delos Recording of Rite of Spring, Hovhaness "The Volcano", James Horner's Titanic, and naturally "the 1812 Overture" DSD conducted by Erich Kunzel. The LDMKI is very good overall in maintaining the warmth and clarity while keeping the sound stage intact, however give the amp an exceptionally fast and dynamic passage (before the LT1364 upgrade), the amp runs out of breath in a rather subtle manner by conveying its audio out to the headphone as though the listener moved from the sixth row to maybe twenty back and forward to the sixth again. Sounds a little weird, however that happens to be the case with the older versus the newer and better designed voltage drive circuit. Let your ears be the judge of which is better. LDMKI or LDMKI+. However with the LDMKI, once the recommended LT1364 from Linear Technologies op-amp replaces the stock LM4562 (by National Semiconductor) then it is extremely close to the sound of the LDMKI+ in sound stage, dynamics, and sonic character while still adding a certain level of warmth that is not quite featured with the newer LDMKI+.
This is not saying much at all since I quite like the LDMKI and MKI+. Closed headphones are the best in measuring these changes since the listener is isolated from the environment that they are in. This is based on my observations however and not other independent source. Using my more than 12000-hours old Sennheiser HD280-professional for use with a full A/B amp comparison, the LDMKI is only a few steps away from the MKI+. Sonic character, sound stage, and dynamics are very close together. The open sound stage that I heard in the MKI+ is also very much present in the LDMKI. Bass extension between the two amps are exceptionally close, in fact so close, it would require a blind test to tell the difference between the two or a new, not fully burned-in headphone to really tell the difference.
This is based on my hearing observation and not the ramblings of a Chinese helping other Chinese with their products. The C&C XO+ is another amp that can surpass the Little Dot MKI/MKI+ in dynamics, however in other regards, the C&C series amplifiers generally lean toward the brighter side, however coupled to a warmth sounding headphone such as the Sennheiser HD650, the certain warm character of these headphones are somewhat reduced.
Conclusion
Like with almost all of the posts that I have made, this one is going to get buried. It seems that we Junior Head-fi members are not treated with the same level of respect as the ones that posts hundreds of comments every year. Time is used for work, play, and hobbies such as headphones, audiophile listening experiences, and for me cycling.
The Little Dot MKI+ is an excellent headphone amp for those who are not wanting to spend the large sums of cash for one for both home and on the road use. Plugging in the power adapter does not change the sound character of the amp to headphones like some amps do because of the voltage supply change. Sound stage is open with virtually no hint in coloration or change from the original recording. Bass Extension is excellent with a good reinforcement and smooth roll into mid-range and then to high-frequencies. For less than $200.00 USD shipped in the United States is excellent money for a well built amplifier.
The Xin Reference is a great amp, however I do find that their amps built in a rather flimsy like manner. It looks like it's going to break into many pieces. Plus their tech-support is rather thin, which when you contact the members of Little Tube, they generally responds within 48-hours. Now that is technical support. I have had no problems with the amp to require me repairing the amp. Although it would seem that the battery in the Little Dot MKI will need to be replaced due to old age. Hopefully with today's battery chemistry that the batteries will be more stable as they begin to age. This is something that i hope for since I now currently have the latest Apple notebook with the eight hour battery. If this was a computer forum, I would tell those who don't think that the Macbook Pro 17-inch unibody can last that long. They way that i use it, I managed 9:15-hours of usage while still having about 5% battery left. That is a long battery life capacity.
I hope that this review will help those who think that by spending a large sum of money will mean that you will get a great amp. This is always not the case. Spending large sums of money on an amp is downright dumb without first considering what a listener is looking for. I have done that in the first initial stages of headphone audiophile listening. Then I started to sample what China had to offer, and then I came to a realization. The Little Dot series is what changed my perspective. I still have one high-end American made amplifier during the days of spending too much money on audio equipment. Now after acquiring the Sennheiser HD800 (I will return in July to open my new headphone for now I must wait), I now have an amp specifically for the its intended purpose, which is the C&C XO+. The Little Dot MKI/MKI+ for the AKG K701, the C&C Box+ for the HD650, and the C&C XO+ for the Sennheiser HD800. I think that this would make the best combinations for the intended headphones. Each one has a character that will best suit for their intended applications.
The last portable headphone amp that I will probably designate as A/B comparison and a reference point amp is the LaRocco Diablo. In all things fair, the Little Dot MKI/MKI+ are excellent amps for almost all types of low and high-impedance headphones. This is my opinion.
Thanks for reading this review and I hope that this thread stays alive longer than the other ones that I have started. Have a great month ladies and gentlemen. Take care and good health.
