or Connect
Head-Fi.org › Head Gear › Headphone Amplifiers › Amp/DACs › FiiO E7 USB DAC and Portable Headphone Amplifier

FiiO E7 USB DAC and Portable Headphone Amplifier

Posted

Pros: Reasonable - works as advertised - no hassle setup!

Cons: Scratched plastic over display (corrected - see text)

Received new FiiO E7 today from Micca in Fairfax, Va (hi ex-neighbor - used to live in Arlington.)

 

Did much reading on this forum and other reviews and truly appreciate the candid and (sometimes) brutal thoughts of recent purchasers.  After just a few hours experience, can only share my first impressions - all of which are positive.

 

Unpacked, reviewed instruction sheet, plugged in USB connector to a Sony notebook running W7.  The Sony found the E7 and loaded its driver, all on its own.  Then, put in classical CD and connected my recentlly acquired Senn HD 650's.  Results:  Wow Wow and Wow!  Maybe a $1000 amp could sound better, but to my older (74) ears, the sound was the best I've ever heard through earphones. 

 

The E7 is very intuitive and just needed the pictorial on which hole to plug each device into to get it up and working.  Was a little confused at first - each time I powered up, it immediately came on then powered down.  Then, needed to read the instruction sheet:  just touch the switch to turn on; touch and hold for a second or two to turn it off!  So easy a caveman could do it (if they read the instructions, that is!)

 

Played around with the bass setting and have found setting #1 and #2 sound best with CD's - #1 for Pop and #2 for classical.  The HD 650's had great presence and I'm hearing sounds that never came out of my modest AV setup with some older Infinity speakers.  Also, tried direct connection to a Sirius Stiletto.  The Stiiletto drives the 650's good - with the E7 it drives the 650's noticeably better!

 

Only complaint and it's minor:  when unwrapping (and it was packed beautifully by Micca, noticed a few scratches on the plastic cover over the display.  Nothing I can't live with, but am wondering what it will look like after several road trips.  But, bought the E7 to listen to, not to look at so no big deal.  At first thought perhaps the plastic was a temporary protector but it appears to be glued in place and not readily removable.  

 

Another not-quite-sure finding:  Does the E7 charge via USB when the computer - but not the E7 - is turned on?   I turned off the E7 to have some lounch and when I checked it out an hour later, the charge had not increased.  Right now, am charging with the E7 turned on and will 'discover' whether this was a solution or not.

 

An earlier post of some time ago was apparently never answered:  how does the E7 work with the Senn HD 650's?  My answer:  Great!   If I'm ever in a high-end store will try out my 650's with a $1K  amp to see what improvement $900 more can make.  In the meantime, I'm quite happy.,

 

My thanks again to the posters in this forum whose comments led me to order and receive the E7.   And,  to Jack of Micca who often contributes to this forum and shipped it packed so well.  BTW Jack, do not believe the E7 package had been opened since leaving the factory, so the scratches were probably done with a chopstick!

 

Regards to all and Thank You.

 

Tom T

North Augusta, SC

 

Correction (the day after):  My dumb error - a kind person sent me a private message suggesting check whether or not a protective film is on the display.  Took me a minute or two to confirm that there IS a protective film in place; thus NO scratch.  My apologies for not recognizing the film and thanks for the kind info.  Will leave the film in place until a proper screen protector is available. 

Posted

Pros: Music is fuller, crisp, instruments are clearly seperated and represented. Great overall value.

Cons: Non so far.

What can I say about this device. It is simply fantastic and for the price you can't beat it I say. I currently use this with my Sennheiser IE8's, Bose IE2's and in my car connected to my stereo and it makes all the difference in the world with all 3 of these devices. I haven't figured out how to use it to bypass my sound card in my computer but I will soon. I know for sure its better than my Xi-Fi card from creative and that alone is a very high end card for a computer. I notice when using the Fiio with all my devices my music sounds fuller, more detailed, crisp in all aspects, highs, mids,lows, bass.

 

Things that I didn't notice before are clearly apparent now and the clarity of your music is unbelievable. I've been showing friends and coworkers how this sounds with my Bose IE2's and they are blown away with the clarity and sound stage. The Bose IE2's are a great improvement from the last gene but man with the Fiio and my Sansa Fuze it really makes them enjoyable to listen to even though I have a pair of Sennheiser IE8's (which are still far superior to the Bose) I still enjoy listening to my Bose IE2's with the Fiio, go figure ;)

 

One nice feature on the Fiio is the bass equalizer. Very simple 0 to 3, I only take it up to 1 though as it seems to interfere with the mids with too much bass but 1 is perfect. 0 sounds great too but its more analytical. I prefer some spice in my music opposed to a more straightforward boring sound. As I said earlier you can plug this into your computer to bypass your sound card which is another great feature and gives your more versatility and overall value. I like how the device isn't overly complicated and pretty much idiot proof.

 

If you are mainly using this with your mp3 player you definitely want to make sure you don't use the 3.5 jack for you headphones to connect this baby to your mp3 as that will cause the amps in the Fiio and the mp3 player to conflict. You'll have to max the volume on the Fiio while also suffering sound quality lose due to the 2 amps conflicting. Get a Line out Dock (LOD) for your device unless your mp3 has that extra port connection for the amplifier then you're set. Fiio sells (LOD)'s for Sansa, Ipod (Eww lol) and Sony Walkman. Basically the (LOD) connects to where your would normally connect your charger/music loader cable to your Sansa/Ipod and the other end connects to the amplifier; while you plug your headphones to the 2 available 3.5 jacks on the Fiio (that's another great feature).

 

Basically connecting your mp3 to the (LOD) completely bypasses the amplifier in your mp3 player and instead exclusively uses the amp on the Fiio. So the mp3 player is only transmitting the music to the amp, I think that will also extend the batter life of your mp3 player so you don't have to charge it as often another plus :). And as the amp on the mp3 is completely being bypassed, even if your using an mp3 player with crappy sound quality (Ipod) you will still get spectacular sound due to the Fiio.

 

The Fiio goes all the way up to 60 max volume and has a memory feature for the volume control. The device also has a sleep timer on it which is quite helpful in extending batter life between charges. I heard the battery can last up to 80 hours on each charge, haven't tested that yet. Finally but not least there is a key lock feature and a USB on off charge feature.

 

Overall I would highly recommend this to the beginner audiophile or to someone who just enjoys music and wants a cheap alternative to the higher priced amps out there. Fiio has a great reputation for sound quality and overall durability from their products, even though its made in China lol. I got mine from amazon from Micca and I've heard of them going as low as the mid $80 range. So if your looking to immerse yourself in the pure exhilaration of music then get this product, you won't be disappointed. Good luck guys and gals :).100_0101.JPG

Posted

Pros: Price, quality, sound, versatility,long battery life,small size

Cons: None

web pic1.jpg

 

I Love this product!  I currently use it at work and home as a USB DAC for my computer. I aslo use it on the go with my iphone via a Fiio's LOD3 cable.  It sounds great from all my sources!  I currently only use it with my Earsonic SM3's IEM's. But what's so cool is that in the future if I want to get power hungry full size cans for home use all I have to do is get Fiio's E9 desktop amp which has a port for the E7 and i'm all set!

The E7 is completely silent, no hiss whatsover.  It has a smooth non-colored high end sound, I don't even find the need to EQ my source when i'm plugged into the E7.  The bass boost is cool, although I don't use it with my SM3's, but it's nice to know it's there in case I get bass light phones.  The build quality is top notch, works on any computer I connect it to, never had a problem with it.  Battery life is insane.  Great job Fiio!!

 

 

 

 

Posted

Pros: durable, has an amp

Cons: sounds worse then my onboard and ipod.

ok everyone i am probably going to get hate for this but i should have ordered the grado sr60s instead. my conexant hd audio sound on my laptop is obviously onboard. from the opinion and belief of people on head-fi is that onboard is terrible. they recommended i buy the fiio e7. so i got $200 for a graduation present and decided to get a fiio e7. i was certain it would make a difference as everyone has been praising it. so after 8 days it arrives. i am so excited to hear what i have been missing. i quickly plug it in and let it charge a bit. i plug my shure srh840 in and at first (placebo effect) i think they sound phenomenal. then after a few songs i plugged my shure srh840 into my computers audio input. and guess what? it is actually clearer and sounds fuller. correct me if i am wrong but i thought there was supposed to be a difference with the fiio e7. i was under the impression it was better then on board sound. i give it an overall 2.5/5 because it has an amp. but other then that this thing is not worth it. i am sorry but maybe this is really just snake oil.  if anyone of you guys are new here. avoid at all costs. none of this improves anything. and the higher up you go the less of an improvement you achieve. i am done with dacs. my on board seems really good in comparison.

Posted

Pros: Build quality, display, two headphone connections, accessories, sound quality, power, clarity, bass boost, battery life

Cons: Distortion as a DAC with multiple audio sources, has to be rebooted. Charging while used causes slight whining on high effinency 'phones

I'll be comparing it with the intergrated chipset in my laptop (Realtek AC'97) and the Nokia X6 phone with and without E7 as an amp, using AKG K 272 HD, Sony XB-500 and Sennheiser CX-300 and Audio Pro Addon One active speakers with a Tangent Evo E8 active subwoofer. Although I was skeptic whether something from DealExtreme could sound nice or not, I was quite pleasantly surprised.

E7 USB DAC vs. Realtek AC'97: Hands down, pants down, the winner is E7. No noise (don't own any really high effinency IEMs or the such but anyway), faster, more detailed lows and very clear and well extending highs in comparison. Compared to the headphone jack in my laptop there just seems to be way more separation to the instruments and music isn't some sort of a blur anymore. Then again I'm comparing it to a really low-end chipset so the difference is quite expectable

E7 as an amp for Nokia X6: overall faster, extends lower and higher, and less muddy. All in all it doesn't sound like the device is struggling to reproduce music with the E7 anymore, and the veiled muddy feeling is grealty reduced. It went three days without a charge, and that's quite good IMO. Anyway, I won't be using any power hungry cans or IEM on the go as of now, so this feature isn't too important for me. Still, it adds to the versatility and value so it's definitely a plus.

Bass Boost: I'm having difficulty deciding whether I like it or not, the sound stage seems to suffer from levels two and three, no matter am I using the speakers or headphones. It's a fun feature, but I'll have to do a lot more testing before I can say anything concrete about it.

Notes: Huge distortion and hiss under Windows 7 and Linux Mint 9/10 when running YouTube, Spotify or any flash applications. Hasa been getting quite annoying lately and I'll stop using this product because of it. Nobody else is complaining so I guess I just got a bad one, but I've lowered the SQ rating to three stars although it's really good when it does actually work.

Posted

Pros: Good warm sound with Wolfson WM8740 soundsignature, Good stand portable amp, variable bass boost, long battery life, sturdy construction, 2 line out

Cons: Soundstage and Instruments separation could be better, after years of use can begin to have hardware problem, no firmware updates

I have the Fiio E7 since 2 years and he's alsways at my side when I open my computer to play music trough Amarra Symphony software.

This little Dac-Amp never deceive me and the first time I try it it wasn't a placebo effect that make me step off of my chair and yeal: ******* SOUND GOOD!

 

As a matter of fact, it was the beginning of a confuse quest about the meaning of a DAC. Before that I wasn't sure it can change drastically the sound, but this was because I wasn't listening the music but just feeling it, wich should be the way to listen to music, but when you develop curiosity for all the frequencies range and their interaction in an acoustical imagery you became as this passionate biologist that want the best microscope to be able to see ALL the details of living cells. You want more, always more beauty, for every type of music you listen.

 

The Fiio E7 is an entry level DAC, it will wow you if you do not have better gear alreay. I can assure it is better than my Macbook soundcard but in no way better than the sound of the Ibasso Dx90, Dx50 or even Hifiman 601. With any computer Dac you should use an appropriate software that will use all the potential of it, plain itunes is not the best. Even VLC is better than this but can make static with flac files.

 

Sound is warm and relaxed, treble is a little roll off and mids are fowards. The low end is spot on and have a 4 levels boost. Must of time I put it at level 1 bassboost and it give my Grado a more rounded and beefy sound, wich sound excellent and give more excitment to lot of tracks.

This is not an analytical or cold DAC, and it's forgiving for lower quality audio format (still I do not advice to use less than 260kb). It sound musical and give more power to headphones, max impedance I will suggest is 150 Ohm, and for full result it's better to keep it under 100 Ohm.

 

I highly recommend the FIIO E7 (E07K now).

Posted

Pros: 80 Hour battery,Portable,Bass sound good at times,Fits in pocket/laptop bag.

Cons: usb receiver limiting the bit rate minor con, bass some times not clean.Have a habbit of dying.

The E7 uses a wolfson Wm8740 for its Digital-To-Analog convertor (dac), The Amp section uses the AD8692 and TPA6130A as Pre- and power amps. The dac does supports higher bit rates, but it due to the usb receiver chip only supports up to16 bit/48kHz. The device gets its power from the usb port or the dock port if it is docked into the E9. The charge last 80 hours when you’re not using it with any power sources.

 

The Amp section headphone Impedance Range is 16ohm-300, the output power is 150mW @ 16ohms and 16mW at 300@, the E7 amp section works very well with my DT770 pro-80s.

The Fiio E7 is one of the older line ups that been replaced by the newer models. It has Two Headphone jack’s which is useful if you’re sharing music with a second person, or using Two Headphones side by side. With a reset hole in the middle of the two which you can use to reset the device.

On the bottom of the device theirs an usb input, which it uses the PCM2706 for the usb receiver. Next to it is the dock connection, with that dock connection the E7 can be connected to the Fiio E9 and use with it as an all in one Dac solution, adapters exist with different functions for that plug. The Aux input is used to plug any other source into the E7, to use the E7 as a standalone amp.

One the side of the E7 are the Volume buttons which are hybrid bottoms which raise or lower the volume, or flip thru the menus. The menu button which on a single press takes you to the settings and select options within the menu. The Power button which turns off the E7 or exit the current setting option in the menu. On the front the E7 has an Oled screen.

There are 3 different bass settings with in the EQ setting which changes the sound of the Fiio E7, Eq0 which is the default, EQ1-3 which changes the bass and the rest of the sound.

 

Intel(R) IPP JPEG encoder [7.1.1]

 

Intel(R) IPP JPEG encoder [7.1.1]

 

Intel(R) IPP JPEG encoder [7.1.1]

 

 

The Setup

I will be using MusicBee set to use Wasapi, for headphones I will be using the DT770 pro-80, The Fiio E7 will be set to EQ 0.

 

The Songs

Chris Bekker – Heimat B (Original mix)

The first thing you hear when you listen to the song is the bass, it hits hard with impact. While the snares are clean and heard. But the drums are a tad hard to hear. The rest of the song sounds nice, with that highs being a tad detailed, it does bother my left ear but not that much. Since that’s where I have HF Tinnitus.

The sound stage I would say is close to you, the sound image is ok to me. But over all sounds good.

 

CloZee – Koto

In this song the first part is really clear including the snares. The bass in this song also have an impactful sound. The vocals sound good as so the clapping in the part where the bass drops. When the bass starts back up it takes the fore front making you notice it.

 

Noisy Blue – Eyes on You

The Song is mainly piano, which in the song sounds really good it has weight behind each note that is played and how heard it being strike. It’s a little bit not clean, But Violins are heard in the background. The sound imaging is ok to me but not perfect. The sound stage is close to my head with this song as well.

 

Slakker – Sailor and the Box

Similar to the type of song as Noisy blue, instead of pianos. It’s Drums, bass, vocals and an electronica note. The bass and the drums hit hard, the snare like the other songs are clearly heard. The vocals are center, some of the voices pans from left to the right ear. Like noisy blue the music is close to your head.

 

 

Over all while with a lot of these songs it did really good job, the bass at times wasn’t clear. But I enjoy using my DT770 pro-80 with it as my primary setup for them. Due to the bass and the portability for my laptop/tablet.

 

 

Updated: The Fiio E7 I had, decided to die on me, no longer charging or any thing.Such a shame but then I just found out that it common for this model, What makes matter worst that you gotta go thru a work around just to change the battery. I don't know what Fiio was thinking  putting the battery directly to the PCB , instead of using a 2pin plug. Since I bought it used can't do a thing about it, but switch to something else for my portable needs.

Posted

Pros: Great amp/dac combo, Easy/no installation, Robust, Excellent price/quality

Cons: Thickness makes it a bit unappealing for portable use

Oh the wonders this little box can do!
The compact yet powerful Fiio E7 is everything you could ask from a 99$ DAC/amp.
After installing the drivers, you're good to go. It gives your music a great dynamic range.
Using it on my Ultrasone Pro 900, with the different bass setting, a "+2" on the bass EQ truly makes the Ultrasone nature stand out. 
This little thing can drive deep, impactful bass with ease. I rarely, if ever, go past 25.
It's a great improvement from my on-board audio card. I don't find myself using it with my Ipod, the thickness of it makes it a bit unappealing, Perhaps I need bigger pockets!
This little box made a great improvement, and I recommend it to anyone that want a small, inexpensive amp/DAC combo!

Posted

Pros: Excellent sound quality and amplification for a cheep price

Cons: Customer support and warranty policy is awful, FIIO does not stand behind their products. Poor quality.

I purchased a E7 with the intention of using it as a headphone amp/dac with my iPod and to use as a dac with my laptop running Audioengine A5+ powered speakers using the optional FIIO L7 line out doc to connect my laptop to the E7. The whole system worked great for about 3 months, but then for some reason the E7 stopped working with my laptop,,,,,still would work with the iPod, but utilizing the DAC with my powered speakers completely stopped working.

I went through the process of going to FIIOs online support but they would not help me in a normal fashion, and pretty much refused to help me through email. Instead they forwarded me a pre-recorded BS response and sent me a ridiculous online form which required me to fill out a huge amount of redundant info I already sent them, I had to actually photocopy my drivers license and attach it to the form...then fill out a bunch of additional crap, save and email the docs to their "support" group.

After all this hassle and time, a day later they sent me another pre-recorded email which basically indicated that they did not even read the stupid form I spent 30 minutes filling out for them. It was clearly a total waste of my time, and it was obvious they read nothing I originally sent them, nor did they look at the stupid form I filled out. In a nutshell FIIOs only response was that I had to send my E7 to their China support center at my own expense, plus they said there was no guarantee they would be able to fix the unit and BTW, it could take up to two months to hear back from them...Huh? We'll at that point I just gave up on FIIO.

It would have been nice if they gave me some advice on what my problem was, offered some troubleshooting tips. Better yet just let me trade out the unit or give me a credit to by another E7. Just Something that made me feel like I was talking to another human being or a company that cared about customer service, In the end I received nothing but disappointment from this company.

Posted

Pros: Good sound. Easy and simple to use. No noise. Easily drives very low impedance earphones.

Cons: Limited to 16-bit 32/44.1/48 KHz streams.

I'm in the UK. I bought this as a boxed ex-demo unit with warranty from a FiiO retailer for £39.99 which is US $64.65 or €47.40

I bought this because my PC's integrated audio is frustratingly bad and other solutions and workarounds were not ideal:

My PC's analogue line out is noisy (electrical interference) and the headphone output is even worse.

It can't drive very low impedance headphones such as my Ultimate Ears SuperFi 5vi Earphones

It hasn't the power to nicely drive slightly less sensitive earphones such as Koss KSC75.

It does have SPDIF optical output and this connects to my ancient Yamaha Home Theatre receiver and sounds great, but that also has high output impedance and so can't drive earphones with very low impedance. It's also a power hungry beast and an extremely expensive way to run small earphones.

I had also previously tried a very cheap USB sound card but this was pretty nasty sounding with good headphones and also horribly badly made (one of those items which can fall apart while just sitting there).

I saw this FiiO E7 offered very cheaply as an ex-demo unit with warranty. I had read several reviews and a good technical appraisal (nwavguy) so went ahead and bought it.

Success! It solves all the above problems. It drives all my earphones and headphones very nicely. It is isolated from all the electrical noise generated by the PC so there is not a sound unless audio is playing. There is no hiss even with the Ultimate Ears SuperFi which hiss with every other thing I ever connected them to. It can push the relatively less sensitive Koss KSC75 to very high levels, easily enough even with well produced music with wide dynamic range. It uses virtually no power, being USB powered, and takes up less space than a pack of cards. That is quite a welcome difference from my giant Yamaha HT receiver.

The sound quality is excellent and seems absolutely neutral and with no objectionable qualities of any kind. I think the bass maybe lacks some impact or dynamics but that is being picky and subjective and is only in comparison with amps that have some serious power i.e. powered by mains, not battery or USB.

I've been using the FiiO with Windows XP and Debian Stable and it works exactly the same way with each. It's automatically recognised as a standard USB audio device and the built in driver does the job. It bypasses the operating system's volume control but by default not the sound mixer. You still can use an individual application's volume control but the system control is fixed to preserve bit depth.

I didn't try anything similar in Windows but in Debian I can entirely bypass ALSA's system mixer (dmix) and make the FiiO exclusive. Assuming the Fiio to be the first sound card (or the only one) adding the following to ~/.asoundrc would do the trick:
Code:
pcm.!default {
type plug
slave.pcm "hw:0,0";
}

This should give bit-perfect audio decoding for two channel 16-bit 44.1 KHz and 48 KHz audio.

The FiiO E7 is well designed, seems well assembled and is very nicely presented with good accessories. I possibly will never use it as a portable amp but I am extremely satisfied with it as a USB DAC and amplifier for earphone and small headphone use. If you have a high quality and really well implemented soundcard and headphone output on your laptop or PC then the FiiO probably won't do anything for you, but for the other 99% of us with rather noisy and low power integrated audio with a poor headphone output the FiiO E7 can make a huge improvement.

edit:

Two years later and I still love this device. Initially I bought it to improve my old PC's audio and it certainly met expectations. In the meantime I've bought a new PC, new USB DAC and new desktop headphone amp so the FiiO is no longer needed in that role. But I've also bought a Samsung Galaxy Note II LTE smartphone which fully supports USB DACs and I've been using the FiiO as an external DAC/Amp with this. It is truly impressive. Smartphone volume out via headphone socket can be rather quiet (power saving is all important for smartphones) so the FiiO adds a whole new dimension to the sound you can enjoy with your phone. It boosts the output levels and sounds fantastic while doing so.

I've also bought the FiiO L7 Line Out Dock (it is inexpensive). This lets the E7 be a more versatile device: a USB DAC/Amp combo, or a portable amp which accepts Line In from analogue source and outputs to headphones, or a portable DAC which accepts USB input and outputs via Line Out to your preferred amp.

This is a really remarkable design, brilliantly executed. There may be other products out there which are similarly versatile and useful but I didn't find them yet.

If I could give the FiiO E7 10 stars instead of 5 I would do so.
FiiO E7 USB DAC and Portable Headphone Amplifier
By:
Description:

FiiO E7 portable headphone amplifier with USB audio decoder (DAC). This product is designed to replace PC on board sound card that do not have enough output power for higher-end headphone. With USB audio decoding, amplification and audio output, E7 can serve as both a professional headphone amplifier as well as an external USB sound card. - TI PCM2706 USB receiver, 48kHz 16-bit support for Windows XP/2000/Vista/7 and Mac OS - Wolfson WM8740 DAC, ADI AD8692 OP Amp and TI TPA6130A Power AMP - High performance, excellent resolution, low distortion, and powerful output - Standard 3.5mm stereo line-in jack for portable amplification with analog audio sources - Dual 3.5mm headphone output jack makes it easy to share music between two listeners - Dual color OLED display with automatic key lock and sleep timer function - Noiseless digital volume control with 60-step precision and perfect channel balance - 3-level bass boost EQ, user definable start up volume and max volume limiter - Specialized dock connector for use with E9 desktop amp for even higher performance - Anodized brushed aluminum case, small and compact, strap to portable audio player - User defeatable USB charging for lower distortion - Build-in rechargeable 1050 mAH Li-ion battery for up to 80 hours of continuous use Specification: - Output Power: 150mW (16 Ohm); 16mW (300 Ohm) - Headphone Impedance Range: 16 ~ 300 Ohm - Signal to Noise Ratio (A Weighted): >=95dB Line In; >=100dB USB - Distortion (10mW):

Details:
DetailValue
BrandFiiO
ColorBlack
EAN0649241870319
FeatureStylish and rugged: OLED color display, brushed aluminum case, silicone skin case
Height2.2 inches
Length3.8 inches
Weight0.22 pounds
Width0.6 inches
LabelFiiO
List Price$99.95
ManufacturerFiiO
ModelE7
MPNE7
Package Quantity1
Product GroupCE
Product Type NameCONSUMER_ELECTRONICS
PublisherFiiO
StudioFiiO
TitleFiiO E7 USB DAC and Portable Headphone Amplifier (Black)
UPC649241870319
Batteries1
Models:
Model Name/TypeMPNEAN/UPC
Head-Fi.org › Head Gear › Headphone Amplifiers › Amp/DACs › FiiO E7 USB DAC and Portable Headphone Amplifier