Perfect deal! Quality is fine.

I had issues with 2 units, one of them had a misprint and the knob default position was off center, the next one also had the off center knob position issue but the sound crackled when the tone button was even lightly touched. I've bought a third unit now, I really love this product so hope the third time's the charm.

I wanted a spare headphone amp for my Sennheiser 6XX that I could just experiment around with, without the bulk. Got the Fosi SK01 for a discount price after reading reviews and was astounded by the quality and sound for the price. It doesn't have all the bells and whistle's but if bang for buck is what you are after, this is hard to beat. Outstanding!

I am SO happy I bought this! What a powerful little device. I was scared about the price tag for (in my mind) such a simple product, but I couldn't have been more wrong. The value I've gotten from this equalizer makes it one of my favorite things I've bought this year. I'm going to feel so naked if I don't have this thing as part of my PC setup from here on out.Easy to use, no installing any software, looks sleek and fits perfectly on my desk right next to my interface. I highly recommend grabbing one if you're like me and don't want to alt-tab to another program just to equalize your sound when that heavy bass dubstep comes on.

Tengo varios amplificadores de auriculares, entre ellos alguno de sobremesa, con componentes discretos y en clase A y algún otro de triodos single ended.Pero desde que tengo éste, no he vuelto a usar ninguno de los otros.La versatilidad de poder ecualizar graves, medios y agudos y aplicar loudness (que por cierto está muy bien logrado) hacen que sin importar que cascos utilice, siembre encuentro el balance tonal adecuado.Muy contento con él.

Customer support:- I should mention this that initial product i received had tone button issues. Whenever I pressed it noise occurred. I thought it was fine as it only happened when music was playing. Later on it added channel imbalances also when pressed. So i emailed fosi support about this and they asked for a video of issue that i was having so that they can understand what issue was. Later support team sent a new replacement unit from china and i got it within 3 weeks. And new one is super good and no problems whatsoever. Initially i was very skeptical about what to do when fosi products start having issues. But after having to talk to guys with fosi support team, I am happy with their response and kind support. I really like their fosi za3 amp so waiting for their newly launched zd3 dac to arrive in india and then buy both as fosi have value for money products.Build of sk-01 is super nice. All metal and feels cold. Knobs rotation is quite nice. Even after using for months its good and no paint chipping off anywhere.Terminations:- Has a line in port at back with a line out mentioned below it which is actually a pre-out as volume can be controlled on this one and a 3.5mm and one 6.35mm port at front. The only thing I really think it should have had is a balanced 4.4mm out so that i could connect my good iems/headphones. Still 6.35mm and 3.5mm are implemented good and they are sturdy.Sound:- I would say if u got some headphones or iems that have some tonal imbalances, this fixes that. Also no noise is audible even on high gain. Some reviewers mentioned it having it a slight noise but thats on some really sensitive iems and u wont have those for casual listening. I got it to have more treble and bass gain for my sony wh1000xm4 headphones. Even though these headphones cost like 30k they arent good. People just don’t know how music should sound like and even me also didn’t knew. Recently I learned some audio professionals info and got to hear how music should sound like and i am impressed. Bought Kiwi ears Cadenza from headphonezone site india and it costs like 3k and still sounds way good that xm4. Now i regret not knowing about good audio quality products at such price exists for a long time. So used SK-01 to match clarity of those iems and since its a headphone its drivers are big, so bigger soundstage. Amp inside of it is nice as its way overpowering for most headphones. Its class a amp i think, not sure maybe check product description. Still it sounds good. Battery lasts around 5-6 hrs when fully charged. Bottom led in my opinion is not useful as it sucks battery power which instead can make device last more longer hrs.Final verdict:- Its a good product i would say for tone controls as aux port or usb c adapters are not that good in audio quality compared to external dacs and this sk-01 can add more power and tonal balances as per your need for any iems or headphones u got. Not only u can add but decrease tones also so do remember that. It can decrease harshness on some iems also. Plus its battery powered so portable. So maybe look into frequency graphs when buying next audio products as most audio professionals don’t like tone controls as they got high priced equipments which are neutral in tonality. Music is personal and for normal priced headphones or speakers or anything, this product is well value for money. Its clarity, build and versatility makes it a unique product that can be used with anything. Price is bit on higher side but u can get it for 7k using card discounts and at that price its good i would say. Not a product u must have but one that u can have for fixing tone controls and add in ur audio products arsenal.

Molto soddisfatto