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From Fatman Itube to ifI ITube (with Audioquest Dragonfly, IUSB and Audioengine A2)

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From Fatman Itube to ifI ITube, a personal computer audio evolution story

In medias res

About two years ago I got a Fatman Itube ValveDock with an included IPod dock and two loudspeakers. This is a very nice looking hybrid amplifier using two 6N1 tubes in the preamp stage, integrated with a transistor amp.

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I discovered quite early, that the sound coming from the included loudspeakers is limited, boxy. So I started to search for a quality replacement for them, and I found the Tannoy Mercury V1, based on the reviews. That time I had a desktop (gamer) computer, and inside that worked a Terratec 6Fire home musician soundcard as the sound source. The 6Fire-Fatman-Mercury chain produced room filling, warm, dynamic, strong, detailed sound at moderate volume levels. I really enjoyed listening to classical and jazz music on this equipment. But there was something that bothered me – during listening to electronic or rock music I felt that the playback became a bit ’slowhanded’, the system did not have a firm grip on the quick changes in the music. Furthermore the 2x13Watt power of the amp seemed to be a bit weak for the Tannoys – from 50-60 % volume distorsion appeared and rose quickly.

Then I received the Audioengine A2 for a try, and fell in love with their voice: great bass for the size, open sound with balanced sound signature in the whole spectrum, enchanting midrange, and the previously missed quickness, freshness.




I have sold the Fatman Itube and the Tannoys, and bought a pair of A2-s. In the meantime I realized that I have less and less time for playing games on my PC, but I listen to music almost continuously – I decided to change the desktop PC to a used Thinkpad X60s, that resides since nearby the A2-s. About the same time I bought my first USB DAC, a FIIO E7, based on the review in What Hifi. During everyday use I found out, that the bass of A2-s rolls off quickly below 60Hz. Following a short Yamaha SW-150 bypass, I bought the Audioengine S8 subwoofer, that complements perfectly the A2. The pure power of the S8 (240W) may seem overwhelming, but using it with 10-15% level, setting the crossover to 70Hz, and following fine tuning of the Phase settings, the S8 seemlessly adds the missing base frequencies.

That time I used the E7 during daily work with my notebook, and connected the A2 with a FIIO D3 SPDIF DAC and a M2TECH Hiface2 async USB-SPDIF interface to the Thinkpad. I think, the FIIO D3 was one of my best price/performance audio purchases until now. An outstanding Wolfson WM8805 USB-SPDIF receiver and a reasonable 24bit/192KHz DAC (Cirrus Logic 4344) worked inside – for about 35 USD. My friend Szabolcs helped me to change the „achilles heel” of the device, the TI LMV358 OPAMP chip to a AD8656, that resulted in a great leap forward in dynamics, without losing the nice detailed and open sound signature as a tradeoff. With such small optimization, the FIIO D3 could compete with DAC-s many times his price. (Unfortunatelly in the follow up product to the D3, the TAISHAN, the WM8805 have been substituted for a Cirrus CS8416 SPDIF receiver – based on several audio forum entries, the new version is less suited for pure music listening purposes). The E7 had considerable advantage in sound quality over the headphone out of my Dell notebook, but on the long term I found the soundstage annoyingly compressed. The logical next step came in the form of the FIIO E17. It used the same Wolfson 8740 DAC chip as the E7, but FIIO emgineers opted for a different USB receiver to enable 24/96 playback, and also changed the OPAMP. The FIIO E17 unsurprisingly shared the warm, bit dark sound signature with the E7, but the sound quality was as different as chalk and cheese: increased detail, micro dynamics, airyness and most importantly the larger size of the soundstage. The E17 became my audio buddy for about a year.

It is easy and very enjoyable to ’make the mistake’ of following the audio websites, forums and magazines trying to catch up with the booming evolution of USB dacs in the last couple of years. In the second half of 2011 the Audioquest Dragonfly became the ‘darling’ of the audio magazines. The most important buzzwords were: 24/96 ESS 9023 SABRE DAC, designed by Gordon Rankin, asynchron USB interface, smaller than a small pendrive (very important one!), does not require USB cable, short signal path, analog level control from the computer, and last but not least the coloured bitrate led. I had to try it out. I have used the Dragonfly with my AIAIAI TMA-1 for weeks, but I had to conclude, that I do not like their sound.

Fortunatelly it was not the the case was with the Dragonfly and the A2. The rich and fresh midrange of the Dragonfly came alive on the open sounding A2, and the Dragonfly succesfully controlled the base frequencies on A2 and S8 pair. The stereo separation was great, I could easily follow the diverse instruments in the mixes. I had only one complaint – the soundstage – they could not fill our small (15-20sqm) living room with powerful sound. I have to admit, that the A2 was designed initially as a desktop sound source, not to stand on a silicon desktop stand on the top of the case, bent towards and firing soundwaves aiming at our couch. It has been written in many publications, that the sound of the Audioquest Dragonfly is very detailed, but can sound a bit hard/digital and flat, and I had to agree.


I really like the sound characteristics of the Dragonfly-A2+S8 chain – the lively midrange, the realistic portrayal of singers voices, separation of instruments – with all the compromise written above. I have tried to find some solution for the flatness, and I came upon the ifi IUSB USB power supply during reading articles about the problems and handling of computer USB power sources. The articles covered all the issues, how the noisy USB power source from the computer raises the noise level of USB DAC-s during music playback: lowering level of dynamics, ruining separation of instruments, smearing the sound of the unique instruments. I decided to give it a try.







The IUSB is the product of Ifi Audio (the new subsidiary of the renowned british high end company, AMR). It integrates two functions: a clean, computer-independent USB power supply, and power filtering. The device can be connected to the computer with the included higy quality blue USB cable.

Besides the USB socket have been placed the socket for the included ultra low noise 9V AC/DC adapter. In the iUSB the power is further ’purified’ in a multiple-step Super regulator filtering process developed by ifi Audio. Between the two sockets resides the switch for the IsoEarth ground noise

elimination system – ifi promises 10x less ground noise using this functionalty of the iUSB – to handle problems with grounding, that is the second most critical noise source for USB DAC-s beneath the power source.

On the other end of the device there are two USB outputs: the first is an integrated USB data + power socket, while the other provides only 5V power. The IUSB can be used in two configurations:

· The DAC connected directly to the data+power socket or

· powering the DAC from the USB power socket and receiving only data through the data+power socket using a V-cable.

It may seem a marketing move from ifi Audio to offer only an other accessory, but it is far from that.

With the help of my electric engineer friend (Szabolcs) we have built a short USB cable, connecting gold plated USB connectors with high quality copper wire taken from an ultra high speed STP/S PiMF CAT 7 cable, and shielded the power and data cables separately, also taking the professional shielding material from the CAT 7 cable, avoiding interference between the power and data paths. Since then I only use this USB cable for USB DACs on my notebook. The look does not justify the audio quality of the cable J - it overachieves easily in soundstage, level, detail retrieval and noise level the mid range audio USB cables I could try. This way I experienced the importance of the separation of data and power wires in USB audio cabling. Ifi Audio produces such V cable called Gemini, and there are several competing high quality products on the market, like the Elijah Audio ISOLAATE BL or a cable from Kingrex.

Following the arrival of iUSB from the italian distributor I was very excited to check how the separate power and data path from the IUSB affects sound quality. Without a special V cable at hand I used a USB cable for external USB hard drives, that can take extra voltage from a second USB socket. This was imperfect, since this cable has taken power from both the power and power+data socket. The power and dynamics of the sound increased substantially, but as a tradeoff the base became less controlled, so I decided to plug the Dragonfly again directly to the data+power socket. Ifi Audio provides a USB- DC adapter to the IUSB, with that the IUSB can be used as a high quality clean 5V power source for 5V audio devices like the Squeezebox Touch.

The installation was very straightforward - it did not require more than a couple of minutes to attach the device to the computer using the included USB cable, and powering the device with the included AC/DC adapter. I did not encounter any problems using the IUSB on several computers – all DACs attached through the IUSB have been recognized immediately by the computers. I have read in some forum entries, that in some cases the USB DAC could not be recognized by the computer – the temporary or permanent disabling of the ISOEarth function was the common solution for these issues. I did not have such problem, so I let on the ISOEarth ground filtering all the time.


Listening experience

Thanks to the substantial lowering of the noise level I could identify and listen to previously unheard details. In the recording of Easy to love from Bass Swing Trio and Barbara Bukle on the Stockfish Records-Art of Recording CD, the voice of the singer sounded much more natural, I could hear even her breath and touch of lips. Her sound moved away from the loudspeakers, it appeared holografically between them. The decay of the resonanse of the double bass strings was very realistic, the resonance of the body of the musical instrument also could come over, and I could paralelly listen to the piano and the diverse types of drums. During listening to live recordings, like on the CD of Nils Frahm called Spaces, in the song Says I could easily and clearly hear the individual noises made by the audience in the background, while the piano solo appeared properly positioned in the foreground. The atmoshphere of the concert hall was represented very convincingly. The wide range of dynamics, subtlety and diversity of his piano playing sounded very engaging. The music sounded much more dimensional, and dynamics became much better without changing the beloved characteristics of the sound of the Dragonfly and A2. With the IUSB the control of base frequencies became even better, more firm. On the recording Rise and fall from Bruce Cockburn I could easily follow the constantly moving baseline, the guitar bends and licks, the diverse types of drums and the bells also played by Bruce Cockburn. The IUSB added those elements to the sound of my system, that were missing/I hoped for: the musical instruments sounded more detailed with more believable touch and decay retrieval, more dynamic and potrayed better in space. The instruments moved away from each other in depth and horizontally. As a result more complex musical arrangements were easier to follow, did not collapse into tiring cacophony. The effect of IUSB is diverse, depending on the DAC it is used with. According to my opinion the Dragonfly arrived into a different league combined with the IUSB. Parallel to the Dragonfly I could listen to the HRT Microstreamer and IUSB combo. In this case the level of improvement was lower. The already meaty sound of the HRT became a bit better defined, and the perception of space, primarily in depth became more realistic.

The IUSB can have the greatest effect on such USB DACs, that does not have independent power supply, but it can positively affect all USB DACs. The DACs without galvanic isolation are prone to the negativ effects of ground noise. The level of improvement depends on the quality of the power management of the USB DACs – based on my experience it is worth a try.

The inclusion of the IUSB into the sound chain had a very positive effect on the sound quality, including the soundstage of the system, but I was still looking for the solution for the powerful room filling sound. It was an additional impulse for me, when I heard Nat King Cole songs (Nature boy, Love, etc) first on the great HRT Microstreamer – AIAIAI TMA-1 Studio Young Guru combo, then on the loudspeakers. On the IUSB-Dragonfly-A2 chain the velvety, shiny character of Nat King Cole’s sound was lost. It sounded detailed and nice, but cold and distant. Memories of the good old Fatman iTube came into my mind. Started to look for ITube MKII (2x25W) amps, but I did not find any for purchase. Parallel to that I listened to some studio monitor loudspeakers (Mackie MR5 Mk2, Presonus Eris E5) to check if the A2 is the limiting factor. ifi Audio started to promote their new product called iTube. Fortunatelly I could convince my friend Peter to order demo equipment from ifi, that landed at me for testing.





ifi iTube



The Ifi ITube is an integrated device, with multiple complementing functions. Ifi calls it The swiss army knife of audio – now that is the marketing J The iTube works solely in the analog domain. A General Electric 5670 NOS tube is hidden in the slim aluminium body of the device.


The only sign of the working vacuum tube inside, is the small red light dot on the upper surface of the iTube, when the device is turned on.

The modes of the iUSB can be set with DIP switches placed on the base surface of the device. With the default setting it acts as a tube buffer without gain with 1 M Ohm impedance. The iUSB can also be switched to preamp mode with 100K impedance. In both cases 6dB gain can be turned on, that can come handy with low output level players, like IPhones or Ipad as sources.


There are two addtional switches on the device for the other two functions of the iUSB.

The Digital Antidote Plus is the enhanced version of the sound improvement technology developed initially by Anthony Taddeo in the eighties. It completes timing and phase correction operations on the analog signal to eliminate phase errors resulting from digital signal processing, primarily from upsampling/oversampling techniques. The information I found about DAP, that it splits the analog signal coming from a digital source, delays one of them with some millisecs, than unites the signals again aiming for a more organic sound.


The second optional function is called 3D HolographicSound. The headphone specific version of the technology was introduced in the iCan. This method corrects the sound of the diverse frequencies according to the characteristics of the human hearing. There are three modes: Off, Normal for HIFI loudspeakers with 2-5 meters of distance between them, and Wide for desktop loudspeakers.


Experience, sound

I presumed, that the ifi iTube shall bring the warm, meaty character of the Fatman iTube’s sound into my system. Based on my experience of two weeks usage, the ifi iTube does not stick to the whole stereotype of tube sound, but fortunatelly also does not contradict that.

As an active loudspeaker user I used the iTube as a pure tube buffer without gain. The iTube did not color the sound, did not emphasise any of the frequency ranges - the preferred sound character of the Dragonfly - A2 – S8 chain remained unchanged. In exchange it brought back the wished velvety, polished character and liquidity of the sound. The digital edge and precise but sterile nature of the sound vanished. The previously rolled off decays became more realistic in space, and the occasionally hard edged sounds produced by the Dragonfly became more rounded. The attention to micro details, vividity, dynamics and the freshness/speed remained unchanged. Fortunatelly these improvements did not bring any tradeoffs with them (like the smearing, slow sound of the Fatman), and the base became more tuneful and tight. Everything sounded more natural.

I tested the effect of Digital Antidote Plus, switching it on/off during listening to diverse types of music. The effect of DAP is more subtle, than the effect of the tube buffer or the 3D HolographicSound function. It smoothes primarily the sound of high frequency instruments, like violin, some wind instruments, and make them sound stronger.

I listened many times to the recordings of Miles Davis - Tutu and Dave Brubeck Quartet – The Last set, with the DAP effect turned on. I felt that in some cases the sound became too smooth and homogene for my taste, I missed the ’bite’ of the brass section, so I decided to turn off the DAP. The preferred sound signature changes from person to person, and level of the effect is different on diverse types of music. The DAP effect can be turned on/off on the iTube making it possible for the user to set the sound according to his/her actual preference.


First I switched the 3D Holographic sound function mistakenly to wide mode – the sound disintegrated in the room, it was horrid. I quickly turned it off, and later on switched it to the hifi/normal mode, appropriate for my setting. The instruments found their place in the space, the soundstage became wider, the instruments seemed to move away from each other, and the sound of base instruments felt stronger and even more tight. As a noticable change the sound of singers moved away from the loudspeakers and walls. The iTube could not eliminate the volume and pure air pressure limits of the A2s, but the system could finally fill our room with dimensional sound.

Some weeks ago I could attend the concert of Brandt Brauer Frick Ensemble on the A38 boat, that was one of the best concerts I have seen in ages. The CD cannot represent how vivid and colourful the concert was, but during listening to Bop, I could easily identify and hear the harp solos, the tight percussions and double bass, the brass section containing a tuba and pozan, the musical jokes like playing the base line with beating the mouthpiece of the tuba or solo played with the strings of the piano, beneath the continuosly pulsating piano base. The complex arrangement did not collapse.

The Nat King Cole songs, for example Love regained the unique sound of the Capitol recordings and the purity, velvety feel, that did not hide the occasional small intentional hardness of his voice. The same could be said about the beautiful Strangers on the shore song from Acker Bilk, that was rediscovered on the Late night tale compilation of Röyksopp. Finally I felt, that I listened to these recordings from a digital source ’in the original form’, not just in good quality.

During listening to the Once upon a time in America Cocoye theme from Yoyoma’s Morricone adaptation CD, the cello almost cried, and I heard the crackles of the instrument at the unrestful beginning of the song. Later on the melody calmed down, and the voice of the cello became warm and soft, showing all steps of the transition in between. I mentioned previously the Barbara Bukle song from the Art of recording CD. Hearing a Chopin Nocturne played by Gergely Bogányi from the same CD was really enjoyable thanks to the special gloss of the sound of piano during the lyric parts, and the full-blooded sound of the piano hammers sticking together with the resonance of the whole body of the piano in the more dramatic sections of the song.

The album SSSS from VCMG presumably will not be a classic of the electronic music history, but the pulsating analog synthetiser sound of the first five songs can easily grip me anytime. It floored me to experience the ringing, resonating analog synthetiser sounds floating between and around the loudspeakers in the room with huge energy – I felt that I could almost feel the sound in the air coming from the A2s.

I would like to mention the elementary power and dynamics of the drum+base startup of Billy Jean, and the clean separation of the elements in the complex base+synthetiser+singing+vocals+guitar solo arrangement in Scream from Michael Jackson’s History album.


Based on the above detailed experience I can say the addition of the iTube between the Dragonfly and the A2 solved my problem, put an end to the flatness, analitical nature of the sound. The sounds became more rounded, palpable, full bodied surrounded with ambience. The iTube borrowed an analog feel to the sound of my system. The level of improvement varied again from DAC to DAC. The Dragonfly benefited strongly from the added subtlety, liquidity to the detailed, dynamic base sound signature. The sound of the HRT Microstreamer is more meaty and analog like (but I feel it a bit compressed used with loudspeakers, that I did not notice when I use it with headphones) – here I did not hear so much improvement.

In summary it seems to me that the systems primarily focusing on detailed sound retrieval, having a bit digital, hard-edged sound (think for example Sabre…) can benefit the most from the addition of iTube. The level of synergy with already analog sounding high end DACs will be much lower.



Some additional songs, and the effect of the iTube on the listening experience

· Vocal

o Janelle Monet – Give em what they love

§ The continuosly present guitar riffs with diverse effects, Prince’s halfways appearing guitar solo, the brass section, electric organ theme and the duet of Monet and Prince all found their place in the space.

o Morningdeer - Concert on a Twig /Drive

§ All small momentum, resonance and the constant changes from almost crying voice to tender or jazzy singing was represented authentically together with the strong guitar-drum baseline, the marching piano, the diverse types of percussions and sound effects – all performed by Krisztina Dányi.

· Rock

o Rolling Stones – Under my thumb

§ The distinctive smooth character, mixing and ambience of Aftermath was present in the song.

o Motorhead – End of time

§ I enjoyed the pure power of the distorted guitars in harmony with the base drums, percussions and hard edged singing of Lemmy.

· Electronic music

o Darkside – Psychic / Heart

§ The drums marching in at the beginning of the song from right to the middle of the space to slowly fill it out completely, the electric guitar jumping in at 1.02, the synthetiser sound becoming unexpectedly huge, and parallel to that the processed singing and guitar solo all sounded very real, convincing.

o Marcel Fengler – Dejavu, Liquid Torso

§ The colourful synthetiser sound and the effects of the song from the album Fokus from the Berghain rezident dj floated in the air around me above the huge, hammering baseline.


Usage, summary

The ITube, as a vacuum tube device, should be switched on some minutes before listening to music to let it warm in, avoiding unwanted distorsion. During continuous usage the device becomes hot, not burning hot, but hot. It should be placed where ventillation is unhindered. The tube is socketed, it can be changed, if needed – screwdriver is included in the package. According to ifi the expected lifetime of the tube is 100.000 hours.

Together with my wife we liked very much the sound of our system extended with the iTube. It is easy to get used to good things. When I had to give it back, both of us felt, that something is missing from the sound. We ordered one as a christmas present.

Closing comments

In this review I shared with you my computer audio experiments. Our recent system can play back all the types of music we used to listen to a very believable, enjoyable way. Recently I could hear the ifi IDAC, that is based on the same ESS9023 chip as the Dragonfly. Unsurprisingly, the sound character of the IDAC is very similar, but the dynamics are considerably better - maybe I shall change for that. In case I have to fill a bigger room with sound, then I shall audition some bigger active loudspeakers. The Adam Audio F7 would come first into my mind, that is starting to build a reputation of a price/performance champion in audiophile circles. Right now I feel, I have arrieved to a system, that provides such musical sound, that fully meets my/our expectations. Further developments are the ’music of the future’ (it is a hungarian slang for ’time will tell’J

There is an important question – how much does it cost, and is it worth to buy?

· Ifi IUSB: around 200 EUR

· Audioquest Dragonfly DAC: around 200 EUR

· Ifi iTube: around 300 EUR

If you ask me, the short answer is yes. The three devices together produce a very detailed, dynamic, analog-like sound, that was the priviligue of the premium DACs costing 800-1000 EUR or above until now, without the tube buffer. I think, that the flexibility of the further development of the system is also a very important advantage.

I could have avoided using a computer for music playback, plugging the IUSB and the DAC directly into the Synology, and playing music with its own AudioStation software, controlled from a tablet. I really like the sound and GUI of Foobar, so I shall set up the wireless controls through some addons in Foobar.

Beyond reviewing these devices I tried to represent in this article, that thanks to the booming development of USB DACs, it became much easier and cheaper to build a notebook based mobile hifi system. Thanks to the fact that I did not have the money to buy a high end DAC 2-3 years ago, without the above mentioned steps I would have missed this period of rising quality mobile music playback, music enjoyment.

Nowadays a FIIO E10 (Wolfson 8740) is worth a try as a first step, that can be bought for as low as 65 EUR. Combined with the iUSB its sound catapults into a different league. Later on the DAC can be changed to a pricier alternative, that also can be used with the iUSB power supply. We should not forget, that these devices are fully mobile, they can be used during working hours with a notebook and a headphone, and arriving home can become the competent sound source for the hifi system.

I won’t say there are no other ways… Many music lovers believe that USB batteries, like the Kingrex UPower provide the cleanest power source. The music specific models cost around the same as the iUSB. The possibility of mobile use made them interesting, but the requirement of constant recharging and the obligatory usage of a V-cable kept them away from me.

It’s up to us to find the system (elements), that fits our sound preference and wallet the best.

Sound system used for testing

· Thinkpad x60, 3GB RAM, 60 GB OCZ Agility SSD, Windows 7, Foobar 1.3 beta 5

· ASUS GX-D1051 V2 Gigabit switch

· Synology DS212j NAS

· Ifi IUSB + Gemini cable

· Audioquest Dragonfly DAC

· USB A-B converter (Conrad)

· ifi iTube

· KáCsa® OCC Line RCA cable

· Audioengine A2 + S8

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