Little Dot I+ 6JI X2 Tube Standard Hybrid Headphone Headphone Amp Pre-Amp Tube Amplifier (LDI+)

**Update with recommendations 9/20/19 at bottom**I'd like to start with all of the information that is relevant to this review. I have been into high-end audio for over a decade now, the entire time as an adult and I am above all other things, a music lover. Secondarily I am an audiophile and former musician of multiple instruments. Music, it's production and the listening experience are what I prize in my free time.My setup is as pictured: Tidal (HiFi) PC - Topping D30 DAC - Topping A30 Amp (using pass-through) - Little dot I+.I'll be frank, are there bad units out there from any manufacturer? Yes. Are the majority of issues with this amplifier setup related? Yes. You wont need to be an electrical engineer to set this up right but there are a few things that will go a long way to having a very satisfying purchase and end user experience.For starters if you use and external DAC (digital to analog converter) this will help. Preferably one that is not USB powered. Why does this matter you may ask and I'm happy to answer. Using your on-board PC sound card or phone or other battery powered device *MAY* create a ground loop. If so, you *MAY* hear humming or buzzing in your headphones when you use this. Just keep that in mind. An easy way to test is to have headphones plugged in to the amp, with the power on, and no RCA cable connected to the rear. If you do this and hear no hum/buzz/noise but when you connect RCA’s you do, then the issue is either a faulty cable or ground loop from a shared ground in your system.So now that we've addressed the most common issue people have had with this amp on with the review then. I have had zero issues with my LDI+ save the fact it's ridiculously loud. I don't listen at "I want to go deaf by 40" levels of sound but I don't play my music quietly either. Even with 300 ohm headphones on low gain I cannot get above 30 on the volume knob. So just accept you may be using very, very little of the volume knob.The good news is the channel imbalance fades out very fast and by about 8 both channels are the same volume. This is par for the course for a device at this price but the volume pot is not scratchy and makes no noise for me during any of my use. I have rolled the Op Amp and have purchased several more to find what I think is best. I also have purchased two additional pairs of matched tubes.Contrary to popular opinion the stock tubes are a lot less "garbage" than people would lead you to believe. If you run them in for about 20 hours you'll find the amp is actually setup pretty well out of the box. I started listening after having the amp on for about 30 minutes and immediately liked the sound of it.Setup is simple and the only thing it doesn't actually cover is how to open the housing of the amp. Google it as seeing it will be better than if I explain it but there are only 4 screws. It takes about 50 seconds or so to do.I have the Vokshod's, and the GE JAN tubes as well. I am currently running in both tubes to the 50 hour mark. The current Op Amp I am using is the Burr Brown/Texas Instrument OPA2134PA. I also have in the mail the AD8066, OPA2107 and OPA2228, all authentic and all purchased from reputable vendors. I will update once the my tubes are burned in and when the additional Op Amps arrive.*Update*As promised, here's the recommendations on pairings.I tried Burson, MUSES, Burr-Brown, and AD Op-Amps. I tried GE Jan tubes, Vokshods and Mullards. I'm going to try to save you money here.Best overall pairing: Burr Brown AD8066 Op-Amp (you'll need to buy one that is already ready to drop in DIP-8. If you search you will find for about $8). Use this with the Mullard M8100 CV4010 5654. You will not have to change jumpers to use this. Outstanding width, depth, bass and vocal. By far and away the best sound I achieved out of this amp.Best for bassier or warmer headphones. Closed backs or those who have more narrow music preferences. Burr Brown OPA2107 (I recommend a legit channel here, about $20). Pair this with the GE JAN 5654W tubes. You can find them on Amazon but I feel like the price is getting a bit outrageous. They were $25.79 when I bought hem and now they have skyrocketed to $35.IMHO these are by far the best two pairings. I'd recommend you try one and if you like it you'll know that the other pairing is also a great option for you. The Vokshods, while good tubes, didn't do anything better with any of the Op-Amps I tried it with vs the other tubes.Best of luck!

First off, this amp is absolutely legendary when paired with Grado headphones, so if you own any in that lineup, make sure you read the reviews on head-fi.org and other sites.Secondly, this amp isn't amazing out of the box. The stock chinese 6JI tubes aren't bad actually, but replacing them should be the first order of business. Read the reviews to find out which tube family suits your taste in music, but this is a pretty versatile amp that can accommodate a wide range of tubes. Make sure you save the two jumpers that come bundled in with the cables. They are very small and easy to miss! This is a bargain and a fantastic sounding amp, but be careful about choosing the right tubes - Grados are revealing and sometimes, static is introduced with the wrong tubes.Lastly, the Opamp is replaceable as well! So you can tube and opamp roll with this amp.The synergy with Grados cannot be overemphasized enough. If you have Grados: SR-60, 80, 125, 225, 325, RS2, RS1 and beyond, these are magnificent and will really make your Grado's shine. The Little Dot 1+ is designed to drive current into low impedance headphones. In theory, that means any low impedance headphone would be great, but that's not the case. I have a pair of Audioquest Nighthawk Carbons that are 32 ohm cans, and they just don't sound right with the Little Dot 1+. My Grado SR-325 on the other hand, absolutely sings. Even in the stock configuration, this amp really makes the Grados come alive. The dynamics, the transients (listen to the Bangles "Hazy Shade of Winter" on a Grado and this amp and watch the drums come alive), female vocals, stringed instruments like acoustic guitar and violin, Blues (Anything Stevie Ray Vaughan sounds amazing), Metal, Rock.The only weak spot appears to be Hip Hop and Dance Music, but that's why I have the Audioquest Nighthawks and a Schitt Magni-Modi handy for those situations.

update:After a few months the hissing is almost gone and it sounds much better. Took a while for the tube to get clean or something. Sounds bad if I output 24bit 192000hz so I have to use 24bit 96000hz. Maybe this fixed the hissing issues.-----------------------------Good amp for the price. It also is nice looking with two capacitors and feels well built with a metal casing. Doesn't get too hot either. One major problem I have is the hum or hissing it produce when output from my laptop headphone jack. With nothing playing it is very noticeable. When I play an new music you can hear it and as the volume gets loader you don't notice it much. I almost consider returning it. I did a test and it has no hum or hissing if outputted from my cellphone or tablet jack. I will buy a USB DAC hoping it will be gone then I can update the score.Sounds,The tube do sound very bright on my AKG 702 which is brighter then most other headphone. I am using 24bit 192khz from my laptop. I also use my bass phone the Bowers & Wilkins P5 e=which doesn't need any amping and does sound worst with this. I was hoping this amp increase my bass on the AKG 702, it just made it a bit brighter, so I will get a different tube later. When I say bright I am referring to very clear to sharp high and mid. It gives ear fatigue after listening too long. I also get ear fatigue with too much bass.