I posted this review over on the LD site a few weeks ago and several folks have asked me to post it here as well. This review takes you from ordering through burn-in and tube rolling. You will see time breaks, these are from additional postings that updated the review as I went along. I freely gave my impressions as they happened so that all types of users would get something from it. So, here it is... Review of Little Dot MK-IVse Headphone Amp/Pre Amp Out of box experience: I ordered my LD MK-IVse on a Wednesday and received it on the following Tuesday! This really surprised me because it came from China to Arizona in such a short time! The box was in great shape and I started un-boxing immediately. The MK-IVse was cradled in poly-foam inserts that keep it centered in the box, away from the sides and tops with about 3 inches clearance all around. The contents of the box were the unit, connecting cords, ¼ headphone adapter and English user manual. The tubes that come with the MK-IVse are pre-installed in their sockets, ready to go. Impressions on initial power up: I ordered my MK-IVse with a green power LED. I could have chosen red, yellow or blue, but I like to listen in the dark at night and green is the least bright of the color selections. After hooking up my Creative Zen Vision player and plugging in my Sennheiser HD-650 headphones, I reached back and flipped the power switch. Power came up without incident and I took a long listen while looking over the unit. Everything about the unit externally is as pictured on the Little Dot Forum, except the volume knob. It has been improved on the “se” model. It is larger with a brushed convex aluminum face that matches the front plate perfectly. The sound tracks I’m using are MP3s at 320kbps, created using my Creative X-FI Music soundcard in my desktop PC from a digital source. I set the volume on my Creative Vision to 23 of 25, which is just under distorting and gave the MK-IVse volume knob a twist to the 12:00 position. WOW! At this level, it is showing off its superior power compared to my old LDII++ unit. The song that was playing first was ZZ Top’s “Give it up” and the first thing that struck me hard was the depth of the bass. Way down there subterranean bass! It was slightly messy, but not excessively. As the song continued, it was apparent that the mids were clean and clear with highs up around 14k. Beyond that, things were too messy to determine any kind of accuracy. As with my LDII++, it was obvious the tubes and the unit needed some burn-in time before I could proceed. I setup the Creative Vision to random play the 450 songs on its hard drive and let the unit play away. Impressions after 100 hour burn-in: At this point, the MK-IVse might as well be a completely different unit! Gone are the messy low bass, replaced with accurate, tight and solid bass. The highs now cleanly extend beyond normal hearing. Accuracy throughout the entire spectrum has tightened up and revealed some shocking revelations. The first revelation was the presence of a wide but pleasing sound stage. It was neither too much nor not enough. The second revelation was the fine nuances that most headphone amps can’t reproduce accurately, like the sound of the drummers stick hitting the ride cymbal, and you can tell if the stick was plastic tipped or wooden tipped. The vocals are so accurate that you can tell if the lead vocalist is facing forward or not. You can hear the bass player’s fingers move to the next note (usually, you only hear the lead guitar do this). Later piano passages sound so real it will make your jaw drop! This was totally unexpected!! I wanted to see if the revelations would continue to reveal themselves when amplified harder, so I ran the volume knob to the 3:00 position. Good Lord! The strength of amplification was outstanding! No distortion, no sign of strain or over accentuation! I had no idea the Sennheiser HD-650s would take this much super clean amplification! This was all just a little too much, so I decided that I should take steps to prevent over stating my findings, so I walked away and returned in a few hours to see if my impressions still matched. They did and more! Considering I am using just the Creative Zen Vision as a source, I can only imagine how great this unit will sound with a good DAC and Disc, Tape or LP source. One thing is for certain, I’m going DAC shopping soon! Impressions after 200 hour burn-in: This turned out to be the fun part. As it was with my LDII++ headphone amp/pre-amp, this MK-IVse has matured into one outstanding headphone amp/pre-amp! That’s right! I have tested it as a pre-amp as well. Here is how I handled the testing. I hooked the MK-IVse up to the AUX2 in on my Pioneer Spec-1 pre-amplifier and decided I would do a direct comparison between headphone results and pre-amp results. Using the same tracks to listen too, I piped the Creative Zen signal through the MK-IVse, and into my main system (Pioneer SPEC 1&4 to Pioneer HPM-100s). I expected there to be quite a big difference between how the system sounds and the Sennheiser HD-650s sound. Wow, was I ever wrong. All of the positive attributes noticed with the HD-650s were present across my main system!! It was clean, clear, tight and wholesome. What I wasn’t expecting was the digital source roughness (even though only slight with the Creative Zen Vision) was completely gone. It sounded very similar to a track off of my Technics RS-1700 Reel to Reel! The sound stage was almost an exact match, with spatial positioning being slightly clearer to distinguish than with the HD-650 headphones. I pretty sure this is due to the HPM-100 speakers and their exceptional high end clarity. Now I just had to try a different source. I piped the output from my Technics RS-1700 Reel to Reel through the MK-IVse and plugged in the HD-650s. Another surprise! I was expecting the MK-IVse to make the highs a little less clear, but that didn’t happen. I was rewarded with the usual “yummy” sound of the Reel to Reel, but I also received the improved sound stage and positioning of the MK-IVse! This is a great combination I plan to listen too often! Other Headphones and the MK-IVse: I kept going back and substituting my Sennheiser HD-650s with my Sennheiser HD-580s, to see if I could find a weak spot in the listening enjoyment. What I discovered was that the HD-580s mirror imaged my findings on the HD-650s, but made the overall sound seem more “Rock” oriented. It was just different, not better or worse. I was totally thrilled with the results! The adjustable “gain” on the MK-IVse was set to “high” for the 300ohm rating on both headphones. Lasting impressions: I have read where the DarkVoice 33x series (latest models) sound great with headphones, but don’t sound very good as a pre-amplifier. Some DV owners have speculated that this problem is not due to the inferior default tube selection by DV, but the design of the pre-amp section of the unit. According to users, if they roll in some superior tubes, the pre-amp problem persists. Combine this with mediocre default tubes and you are in for disappointment right out of the box. The LD MK-IVse exhibits no such deficiencies and sounds almost identical using either the headphone out or pre-amp output. This is obviously due to the MK-IVse’s superior design and build quality. One peak inside this unit and you are treated to some of the best components and craftsmanship on the market. The MK-IVse does not get hot, even if you are taxing it to the maximum (unlike the LD II++ unit), and it has truck loads of headroom for those super dynamic passages! There is NO grounding noise, line interference or RF intrusion either! The locking headphone jack is a really nice feature and the selection of default tubes for the “se” model is superior to all of its competitor’s default selections that I have seen. I consider the fit and finish of the MK-IVse to be superior to others on the market, in the same class. The type of case, paint and polish are clean and professional looking. The golden plate with attached golden tube guards looks very cool, especially at night when they give off a nice golden glow! Tube “rolling” possibilities are restricted to the same family of tubes, but it is this family of tubes that helps achieve the superior sound quality in the first place, so not much “tube rolling” will be necessary anyway! Now I’m sure you are wondering if there is a negative side to the MK-IVse. To put it succinctly, no. Every tasking I threw at the MK-IVse, it responded with superior sound quality that will not disappoint even the most demanding of audiophiles. Some users might want additional analog or digital in jacks for their other equipment to be hooked up. Once you realize that the “cost” of producing the MK-IVse has gone into “ultra-quality” components, those jacks don’t seem quite as important. It would make better sense to purchase a high quality multi-featured DAC to use with the MK-IVse. This is what I plan to do so I can run optical digital in and listen to headphones. Price wise, the LD MK-IVse is on par with competing units, but represents a better “bang for the buck” in power, quality and support. Conclusion: For the headphone amp and tube pre-amp buyer who wishes to purchase a unit, plug it in, burn it in, and then just enjoy the music, the MK-IVse is an outstanding unit to fulfill your needs. You will have everything you will need for years of uninterrupted enjoyment. For the buyer who wishes to dabble in tube rolling a little, listen to headphones some, use the pre-amp some and generally use a new unit to its fullest extent, the MK-IVse is a custom fit for your needs too! For the buyer who is a “Tube Rolling Fanatic”, I would recommend the MKIV regular version. It has the ability to switch from the default family of tubes (like the “se”) to the same family of tubes used by the LD II++ unit. This will give you an additional 10-15 possible tube selections. The MK-IVse is a “muscle car” in the power department, which will blow you and your favorite music away! For the first time in a long time, I can say with absolute confidence, get out your wallet and purchase the superior LD MK-IVse. You will not be disappointed. Congratulations go out to David, Sword and the others at Little Dot. You have once again proven that audio done right, has great might! UPDATE 6 DAYS LATER... Well, the MKIVse is turning out to be a far better unit than I could ever hope for. Everything seems past any kind of break-in period and I have about 300 hours on it. Last week, I ordered a setup of tubes (Phillips Jan 5687WB) to take the place of the Mullards. I JUST CAN'T BELIEVE WHAT I'M HEARING! These tubes sound better right out of the box than the Mullards did after 200 hours break-in. I ran them for @ 50hours and they improved even more. I turned right around and ordered another set for spares! So completely High-Fidelity these new tubes are, I'm done tube rolling power tubes from now on. I have some GE 408A's, WE 408A's and Sylvania 408A's coming, so it will only be driver tube rolling from now on. I have never heard a tube like those Phillips 5687WB's before! They are top dog on my list now! Extremely Highly Recommended even at the higher cost. UPDATE 4 DAYS LATER... Well, I’ve been using my MKIVse for over 400 hours now. I believe it is done burning in. From the 200 hour mark, there have been final “icing on the cake” changes I had not expected. The most obvious has been an increase in headroom (The amplifiers ability to cleanly drive music without draining its reserves and distorting). I can now turn it way up, to the point of hurting my ears (just once to find out), and it did not distort or become shrill. It just amplified it more and remained clean. The second most noticeable has been a final improvement in the lower end bass. If I had to describe it, I would say it is reproducing the bass without coloration or over amplification. Nice clean, tight and subterranean bass. My favorite!! I would also like to offer up a little advice for those who are shopping for an excellent headphone amp. If you are looking for the best bang for the buck, buy the MKIII. If you have the extra money and want something slightly more powerful and refined, buy the MKIV(standard). If you are not concerned so much about the cost, and want one of the best tube headphone pre-amp / amps on the market, buy the MKIVse. Whichever model you choose, you will NOT be disappointed! UPDATE 7 DAYS LATER... Well, the Tong-Sol's are burned in. Every part of the audio spectrum has tightened up. They reach WAY down to subterranean bass levels and extend up to super high levels, cleanly, without any drop off. They are fantastic tubes. At first, I thought they would just be "rock" tubes, but once the burn-in was done, I tried Rock, Jazz, Soft Rock, Classical and orchestra. All of these sounded amazing!! They are not mellow like the Mullards. They are crisp, clean and detailed. So far, here is what tube rolling has revealed to me: Power Tubes E182CC Mullards = Mellow and beautiful to all kinds of music 5687 WB Phillips = Clean, wide sound stage, increase in dynamics for all music 5687 WB Tong-Sol = Crisp, clean, detailed and dynamic for all music Driver Tubes 408A W Elect = Best definition and punch through out. Very full spectrum 408A G Elect = Less over all definition, punch still on bass end of spectrum 408A Sylvania = Almost identical to G Elect 408A G Elect 5 star = Almost identical to W Elect, slight improvement in vocals As you can see, one noticeable trend is that the Power Tubes (no matter which) work well with all types of music. Very cool indeed! All of the Driver tubes sound wonderful, so interesting changes between them, but all are great tubes. What is fascinating to me, is when you mix one set of Power Tubes with a different set of Driver Tubes. Some very interesting combinations can be made!!! My favorite so far is pairing the E182CC Mullard Power Tubes with the 408A G Elect 5 Star Driver Tubes. WOW! What an amazing sound combination! I still can't identify what I'm hearing, but it sure is sweet! Second favorite would be the 5687 WB Tong-Sol Power Tubes with the 408A W Elect Driver Tubes. It is more of a "super" all around combination. I could listen to this combo from now on, and never roll another tube! (maybe) Anyway, I hope this can help some other MKIV users get an idea of what tubes to be looking for. They may sound different to you than with me, but I will say that none of them will sound average or poor after burn-in. I am sure of that! I'll update this list as I do more. Dave McLaughlin LD MK-IVse owner and Audiophile since 1977 *****UPDATE UPDATE UPDATE AS OF 01-11-08 UPDATE UPDATE UPDATE***** Word from DavidZ at Little-Dot, about the MKIVse and it's default tubes: "The WE408A is a 20V filament tube so the front driver tube voltage is modified to 6.3V for the M8100. The rear 6H30PI has a different pin-out and characteristics from the E182CC. At this point we are completely out of the E182CC vacuum tubes, and we have a few months supply of the 6H30PI left. Therefore all MK IV SE from this point on will be M8100 and 6H30PI version until we run out of 6H30PI tubes, at which point the MK IV SE will be discontinued. I hope this helps!" So, from now on, the MKIVse will be hard wired to use the M8100 and 6H30PI tubes. When Little-Dot runs out, the "se" version is all gone. The MKIV and MKIVse are real power savers!!! The average power usage is only 30 watts!! 1/2 a light bulb! Love it!!!