Instant 5 star as soon as I plugged it in.

In the box you get a short 3.5mm TRS male to male cable, and a longer one. I love the shorter cable because I already had a female to male headphone extension cable from the Wave XLR interface on my computer.

I plugged in the HD600 headphones from Sennheiser and I'm pretty sure I have not been listening to music (or anything) the way it should be. UNREAL clarity, bass, it really brings out these headphones. PC cards/interfaces without a pre-amp for OUTPUT cannot drive these. My interface drives mic pre-amp but not sound, this is an amazing breath of fresh air.

Having a knob on the interface for volume is great too so I don't have to reach the interface or fumble in windows. You can keep volumes on max or the highest level you want, then use the LVY amp to control gain. If you're not "hearing it" and need to take it to 11, there is an "H/L" switch on the back, swap it to H for high level input and feel about a 20% boost compared to L. What this does for me is increase the low end as well so you get a narrower band of volume, but it does go higher. Think of it as a spike in an audio graph. I prefer a more gradual increase so I'm on L for now.

You can charge this and take it with you, use with a phone or another input device, doesn't just have to stay attached to the charge cable. I think it's supposed to have a long batter life so we'll see, but I'm usually near a usb A input so I should be ok.

If you have over ear headphones or power hungry headsets these will benefit big time from this device!

Cannot believe the price for such value. If you spent a lot on phones, this extra $$ is not a question, just get it.

The product worked as expected for me I had sufficient amplification on an external speaker I was using

In my opinion this is a wonderful product for people who are looking for something to boost sound! Now if you have crappy headphones you would probably have crappy sound with no bass.

The Dilemma! (with LS2 helmet)-
My purpose for this product was to enhance my sound quality and volume for my cardo smart pack system while riding. And of course the original headphones to this system did not work for me. (Buzzing Bee Sound) Ear placement could never be fixed. The pads were way to small and the person who install my system thought it would be a great ideal to cut into the foam of my helmet. So I was back to ear buds and I really didn't care to use the cardo system or the helmet unless I really , really had too! (husband has cardo system, we love riding together and I tend to be very talkative in which he finds it funny!)

Solution!
1. I replace cardo headphones to (over the ear)! This fixed my sound quality and reduce wind noise by 50% with no ear pain from pressure.
This product did not change the sound quality; meaning the bass, the clarity,and the treble of the headphones. I brought headphones that had bass, treble, clarity. which overall improved the quality sound.
for example : if you like headphones with bass then buy the ones with bass.
This product just made it louder with no interference or distortion.
If you experience interference or distortion it may be the way that you are to connect the device or the crappy headphones.

2. I then connected the amplifier directly to headphones and the cardo system via 3.5mm splitter($3.97). Note: You have to choose one or the other but not both! Connect amp to phone or connect amp to headphones otherwise the device will not work properly! this was the reason why it tool me soo long!! I was trying to connect amp to phone and headphones. Please choose what works best for you. Connecting to headphones worked 10 times best for me! because i wanted to boost the sound from headphones. my music was bluethooth from phone via cardo so there was no need to connect headphones to cell phone. hopfully that made sense.

3. I am now able to max volume on Amp fit it with my phone in my jacket pocket and Control volume from cardo device! I can now listen to my music and speak with cardo system.

Any over the ear that is easy to dissemble for YOU!! This took me while but I saved SOOO much money!!! I didn't have to buy a new helmet! I am a female, 5'3'' and
I weigh about 136lbs. I already have 3 helmets ( I have a small head so depending on the hairstyle. will determine what helmet I wear (small/medium/large)!

the shipping was fast! Product made of great quality (it doesn't feel like it was cheaply made) So far I have not drop this product. it has exceeded music time and talk time for me . I took a 2 hour ride(GA to SC and back a total 4hrs to 5) using this. my battery did not die or drain.

My headphones was under $22 splitter about $3 to $4 vs. spending more money on another helmet$199-$600 or more and then another cardo system and speaker
upgrade because I would probably want 1 for every helmet that I own! You do the math!

I got some movies in file with 2 low of sound. I would have gave it a five star if you could leave off and connected and it bypassed so I wouldn't have to leave on when I didn't need more volume. I use speakers from my 3.5 a&v on TV as I can't hear the TV speakers clearly. I was able to tape a connector to unit so if I need amplification I can unplug from connector and plug into unit. I did same with USB power plug. It's taped to USB power. I just got to plug into power disconnect from connector plug into unit. Then it only runs when I need amplification.

This amp has worked nicely and is exactly what I needed.

I primarily use it for voice recording. When recording, I have the gain on my audio interface low, but that also means I couldn't hear myself through my headphones while recording until I would listen to the playback.

This helps me boost the level so I can hear myself in real time without touching my gain adjustment. If you plan to use it the same way, just make sure you turn the volume down before you listen back to it or it will be super loud.

The quality of the casing and buttons are nice as well. Nothing feels cheap and the casing appears to be metal to likely act as a heat sink. I have never felt the unit even get warm, so it serves its purpose well.

The charge port is a micro USB. You can charge it through your computer or with a phone charger. You can't charge it while you use it or it creates a lot of feedback. But the battery life is very good, I think I only have to charge it every few days. Charge time isn't bad either. I'd forgotten to turn it off before and came back in the morning and it was still running. I just leave a charging cable ready at my desk so I can charge this amp or my bluetooth mouse with the same cable when needed.

I plan to also use it on my outdoor projector as because the projector seems to be picky about audio inputs.

I've been working with this amp full-time for work for about six months and I have absolutely no complaints.