Intro

The diversity of audio products grows just as the market of portable audio sources like phones, tablets, portable hi-res audio players, DACs. We use them for music listening and every so often plug them into our home stereo systems or car audio, we plug our sources at our friends’ homes to boast our music collection and so on. Many of such portable devices have good DAC chips but unfortunately not so good output stage due to size and components constraints such as op-amps built to a lower price point resulting in less than ideal output impedance when you try and use them with mature stereo systems. The resulting intercomponent impedance imbalance can have varying degrees of influence on the sound you hear.

Initially I thought this mismatch was not something I should really care about and diverted attention elsewhere until I was offered to try and test Burson Audio Cable+ Pro and express my honest opinion about it. Being extremely curious, I could not resist the temptation so here is my review.

An Expensive Cable Sounds Better...

...just like a red car drives faster That's my position when you ask me what I think about hi-end audio cables. I'm a strong believer that there is no audible difference between a $5 oxygen free copper cable and a $500 oxygen free copper cable and I still am. Before even trying Burson Audio Cable+ Pro I had to prove my point on ordinary cables. So I bought the cheapest cable I could find for $5 to compare it with some expensive cables in my own inventory, won't call names though. I also ordered a handful of different adaptor cables and splitters for various connectivity options.

In the picture below is my inventory of cables and adaptors I used throughout the review:


I have my proven reference portable audio rig which I carefully assembled with many of trial and error and $$$$ spent in search of the most pleasing and quality sound to my ears. Let the image not fool you, it's total cost is over $2000.



High level list of main components:

• Headphones: Balanced Beyerdynamic DT150 (250Ohm) studio headphones
• Headphones Cable: Balanced OFC copper handmade cable
• Amplifier: iBasso PB2 with MUSES01 or Burson V5i Dual OpAmps + LT1028ACN8 buffers in balanced mode
• Power source: XP8000 external battery (16V power supply for the amp)
• Source/DAC: Fiio X5 (PCM1792 DAC)

My wife helped me with a series of blind tests. She swapped a pair of cables at random, played the track, then swapped again and so on until it was done 10 times while I was sitting with my back to her wearing headphones, listening and writing down the results. Then we would compare the results.

We repeated the test for each pair of cables:

• 5$ AUX-RCA cable + AUX adaptor <---> $100 AUX-to-AUX cable
• 5$ AUX-RCA cable + AUX adaptor <---> $50 AUX-RCA cable + AUX adaptor

TEST RESULTS. The average guess rate was between 40-50%, which is basically 50/50, meaning I could not hear the difference between a $5 cable (1.5m long) with an adaptor and $100 solid custom ordered cable (50cm long).

If you told me that you purchased a $5000 cable, I would simply reply that you overpaid $4995 for it. It's a joke but with a grain of salt I personally wouldn’t want to use the cheapest cable in my audio chain because it simply doesn’t feel right but rather buy a cable of appropriate cost to match average price of audio gear.

Burson Audio Cable+ Pro Sounds Better?

Does it? How is it different from a $5000 cable? Well, it is not just a cable. I'd rather suggest you think of it as an active audio component with integrated discrete circuit which plays as buffer to fix impedance mismatch between the source and the amplifier at the cost of higher gain with connectors attached from both sides, which must be powered from the mains or a USB port.

My domestic elephant convinced me to have a photo session with him and the cable:





Cable+ Pro comes in a plastic case of the size of a VHS. At least that’s what my wife noticed when she saw the box first time. ‘Is that a VHS?’ she asked This would give you the idea about the size.

All necessary accessories come with the cable:

• USB to micro-USB cable
• Mains adaptor

You need is to plug micro-USB into Cable+ Pro and the other end into the adaptor and into the wall socket or power board before using. A blue light will come on:


There is an alternative way to power the cable. You can use a USB power bank, which will also do just fine:



Now that we are done with the cable on its own, let us see how it performs in action, how it is compared to ordinary cables and how it plays with different sources/DACs from the list:

• iPhone 6s
• Chord Mojo
• Fiio X5

I used my home stereo system as guinea pig for testing. I made it from the following components:

• Yamaha NX-N500 powered studio monitor speakers
• Yamaha WXA-50 amplifier/receiver
• Yamaha NS-SW300 subwoofer
• IsoAcoustics Monitor Stands for speakers and subwoofer with patented "floating" architecture for audio image stabilising

I used RCA audio splitters to connect two cables simultaneously to the receiver for future blind testing:



I used Fiio X5 as the primary source/DAC component connected to the receiver for initial evaluation:



Below is my standard list of tracks, which I use for critical listening every time I need to compare or evaluate something. It consists of vinyl records converted to 192kHz/24bit FLAC format and some CDs in FLAC:


Dire Straits - You and Your Friend (Classic)
Pink Floyd - Mother (Classic)
Metallica - Fade to Black (Metal)
Год Змеи - Код доступа (Rock)
Владимир Высоцкий - Вариации на цыганские темы (Russian chanson)
Skip James - Hard Time Killing Floor Blues (Blues)
Gareth Emery - Save Me (Trance)
Lindsay Sterling (Violin)
The Piano Guys (Piano, Cello Instrumental)
Woods of Desolation – Somehow… (Depressive Suicidal Black Metal)

First Impressions

Absolutely fantastic!

I could not believe my ears. I thought that my brain was playing a trick on me, so I swapped the cables back and forth a few times to only confirm what I hear. What I want to stress is the overall impression from the sound stage as a whole improved. It felt as if I have just converted my whole stereo system one level up, as if looking at the painting in the art gallery someone shed light on it making all the beauty of contents and details to stand out, become more prominent and that's what I call positive and quite substantial changes. Even my wife, who is not accustomed to critical listening and to listening to high quality music, found Cable+ Pro quite engaging compared to an ordinary cable.

I am very critical and very picky towards sound reproduction quality and I always evaluate whether a change is a positive or a negative one regardless of the price I paid for audio gear. Several expensive pieces of gear already played a trick or two on me so I had to return or sell them. With this piece of gear though, I can definitely say it improves the sound quality to an extent I could hardly believe in audio terms as normally most of the changes are subtle and more or less subjective. Nevertheless, I had to run blind tests to move odds to objective territory a bit.

Blind Testing

Blind testing is necessary to exclude your brain as variable from the chain of evaluation process because this part of you is a sly and cunning creature - it will tell you something that does not exist and you will believe it only to justify your newly purchased audio toy. We don't want that, so blind testing we do.

I mentioned earlier Burson Audio Cable+ Pro buffers the signal. It means that it adds a little gain so the volume increases as soon as you swap cables, hence, I asked my wife before swapping cables to turn the volume all the way down, then swap the cable and then increase the volume at variable rates every time the change is made and do so 10 times per session. As part of blind testing, it was the tester’s objective to fool the listener (me). That is why she could disconnect and then reconnect the same cable back again to make it more fun and challenging.

Test results showed 90% guess rate or 9 out of 10 guesses were correct, which is very impressive.

Since blind tests were done with Fiio X5 as source, which proved that it was not my brain that played a trick on me rather than the sound actually improved quite a lot, there was no point in doing more blind tests with other portable devices so I simply listened to them.

iPhone 6s:



Chord Mojo:



Same good results. Although with Chord Mojo you need to keep in mind increased gain of Cable+ Pro. Chord Mojo by its nature has a non-standard higher LineOut voltage so if you have one in you hi-fi setup you will have to decrease it from 3V to 2V to avoid clipping and distortion at heavy bass sections in music. It is only four clicks away anyway.

Cable+ Pro Gain

Speaking about Cable+ Pro gain. It does add gain to the initial signal. Let’s find out how much. I did not bother to get pink noise so I simply played a bass heavy track from Fiio X5 LineOut connection to use as reference and logged maximum voltage output at its peaks.

With a standard audio cable, it reached as high as 0.6V.



With Cable+ Pro it reached as high as 1.2V at peaks:



That’s how much gain we get using Burson Audio Cable+ Pro – twice as much. It does not mean though that your actual volume will be twice as loud. At the same volume setting the sound would be about 30% louder.

I’ve been wondering if I could consider this cable as some sort of a pre-amplifier in addition to its key function of correcting impedance mismatch so I asked this question to Burson representative and the answer was to treat the cable as buffered cable only.

Direction

Cable+ Pro is a directional cable. It clearly says so on its back:



It also warns about powering on the cable only AFTER all the outputs are connected.

Well, I am Russian and Russians don’t read instructions. Even if they do, they would still try to do everything their own way. I’m joking of course, but I personally did everything the wrong way and found out:

1. If you connect the cable the other way round, there won’t be any sound so it’s pointless to do so.
2. During testing, I did plenty of connecting and disconnecting with the cable being powered on and nothing happened.

I strongly suggest not to repeat those steps at home as you may eventually damage the cable or your equipment.

Summary

Go for it! The price of Burson Audio Cable+ Pro is pretty much justified for performance gain you would achieve. In other words you will get more performance for the price.

The elephant is happy!

Intro

 
I still remember that day when I received Burson V5i Dual Opamps in my mailbox.
 

 
It was 3 days prior to passing my 8 hour long engineering lab exam of my life to finally get certified under the CCIE program. Before passing the exam I could hardly do anything else but to sit in front of multiple console screens all days long for over 500 hours taking breaks only to have some sleep, eat and attend work of course.
 
Now when the nightmare was over and I could have my life back again there was a couple of Burson V5i opamps lying on my table still unattended. They would just come in handy, I thought to myself, to have a good round of yet another music listening experience and joy of opamp/buffer rolling in never never-to-get-old iBasso PB2 balanced portable amplifier, the most powerful portable amplifier on the market, which can give a head start to many multi thousand dollar table-top headphone amplifiers if chosen the right out of thousands available opamp+buffer combinations.
 
  
 

Experience and Setup

 
Before diving into the review of Burson V5i opamps I would like to give insight into my overall personal audio listening experience. In my opinion, having a diverse experience is very important in order to be as much more objective as possible on such a subjective matter of sound analysis.
 
Here is a brief list of the audio equipment I had honour to audition. Only the brands which I remember:
 
Full-size Headphone Amps/DACs:
 
Beyerdynamic A2 (DAC+Amp)
Burson Conductor V2 (DAC+Amp)
Chord Hugo TT (DAC+Amp)
+some many other hi-end Amps/DACs
 
Portable Headphone Amps/DACs:
 
Fiio E12 (Amp)
Corda Quickstep (Amp)
iBasso PB2 (balanced Amp)
iBasso D14 (DAC+Amp)
Chord Mojo (DAC+Amp)
 
Full-size headphones:
 
Audio-Technica ATH-M50x
Audio-Technica ATH-A700
Beyerdynamic DT150
Beyerdynamic T1
Sennheiser HD800
Audeze LCD2
Audeze LCD3
+many others
 
Opamp ivnentory: Burson V5i, MUSES01, LME49990, NJM2068, LM6172, LME49860
 
Buffer inventory: LT1010, LT1028ACN8, Dummy buffers, and others...
 
I must note that I no longer believe in the most common misconception which states "the more expensive an audio asset is the better it sounds". It matters only to an extent beyond which it doesn't matter any more. The "extent" is very subjective, so there's no point announcing mine. All that matters is I never take the price into account to evaluate the sound reproduction properties of the gear.
 
I had many trial and error to build my reference setup. Prior to auditioning Burson V5i my audio rig had the following specs:
 
Headphones: Balanced Beyerdynamic DT150 (250Ohm) studio headphones
Headphones Cable: Balanced copper handmade cable
Amplifier: iBasso PB2 (MUSES01+LT1028ACN8) balanced only mode
Power source: XP8000 external battery (16V power supply for the amp)
Source/DAC: Fiio X5 (PCM1792 DAC)
 
 

Sound Signature Adjusting

 
The Golden Rule to any audio combination is the synergy between headphones/speakers and DAC/Amp. For example, it can be referred to pairing a darker sounding amp and with darker sounding headphones which will overwhelm you with bass and cuse fatigue in the long run. But since we are speaking about opamps, one has to carefully consider the choice of buffers to match (i.e. add to) the opamps' signature and reveal their potential.
 
A good example regarding Burson V5i is the following:
 
1. Dummy buffers are extremely good with LME49990 but combined with Burson V5i reduce immersion and flatten the sound-stage of V5i.
2. LT1028ACN8 buffers match well with bass starving MUSES01 but combined with Burson V5i they greatly expand deep low frequencies reproduction introducing darker 3D sound stage which might be acclaimed by bass heads but it comes at a cost of depriving reproduction from some higher frequency touches making, for example, a violin's pitch to become less prominent and less touchy. Bright headphones might be a good solution to even the balance. PS. After another set of buffer rolling the signature with these buffers seem to have improved. They now sound pretty good with violins and guitars. Might be either my brain or the opamp burned in, hmm))
3. LT1010 is the golden middle with Burson V5i...but you should still try buffers from number 2 above  
 
If buffers are irreplaceable one would have to adjust the sound signature by trying another set of headphones. My assumption is that brighter headphones will do better than darker with Burson V5i.
 
NOTE: And that's another beauty of iBasso PB2. I don't need to replace headphones, hence cost savings  
 

Impressions

 
Honestly when I first plugged in Burson V5i opamps and played first compositions I was attacked by so many goosebumps that I can hardly remember having that many ever before. It was a different new sound characterised by integrity, thickness where everything seemed to have volume as opposed to hollowness and airiness of bright sound and have its place in the overall 3D soundstage. It was a bliss. It was a warmer sound signature much warmer.
 
A week passed, I settled and got used to the new sound now and can speak about pros and cons of new Burson V5i opamps with clear head. When I am speaking about these opamps I am speaking about them in combination with LT1010 buffers as those reveal the true musical nature of Bursons best and transform the concept of listening to music from hearing it to feeling it.
 
With Burson V5i opamp + LT1010 buffers installed the setup looked like in the picture below:
 

 
Burson V5i are darker sounding opamps. Cellos, bass, double bass, alto saxophones in Jazz and Blues represented by V5i sounded exceptionally good and natural. As an example, I never listened to The Piano Guys with MUSES01 installed in the amp because my brain was rejecting unnatural bass reproduction. With Burson V5i, on the contrary, now I can't help it and listen to this music over and over again. Same refers to any Jazz, Blues, Instrumental or Orchestral compositions with higher dynamic range especially. Even Apocalyptica's album Reflections (2003) which has dynamic range of 6 (six) and what is considered to be bad on DR scale now sounds great. Hard Rock and all Metal genres have a bigger punch and presence.
 
Binaural recordings are amazing and more real and intimate with Burson V5i as well.
 
Although Burson V5i excel at Instrumental/Orchestral, Metal, Jazz/Blues and Binaural recordings they lose the battle to MUSES01 and/or brighter DACs in Classic Rock where acoustic guitars dominate the scene. This also refers to any acoustic guitar passages in other musical genres as well. It happens because of an overall warmer nature of V5i opamps which make acoustic guitars have a slight tint of bass and suppress its clarity and crystallity. But the lack of spaciousness and brightness is compensated by the full body sound presence, volume and 3D appearance which I am afraid cannot be presented by brighter amps. Brighter DACs/Amps can give incredible, huge cold scene as if you are in a concert hall with separation of musical instruments scattered all around you. This is good for some and bad for other reasons at the same time. Warmer ones like Burson V5i opamps are more intimate, integral, real, natural and more 3D like producing a complete musical scene. I would stress that Instrumental music especially is the most breathtakingly reproduced by Burson V5i.
 
Actually the same refers to full-size Burson Conductor V2, which has almost the same sound signature as little Burson V5i opamps. Burson Conductor V2 was dark sounding when I auditioned it last week, so I had to replace Audeze LCD3 with LCD2 for obvious reasons that LCD3 are already dark headphones and multiplying it by x2 equals to almost pitch black darkness))) What does it say? It says that Burson V5i opams are really that good on their own if in optimal circuitry.
 

Direct Comparison

 
Now that I have shared my impressions I will pick up hi-end MUSES01 opamps for comparison. In this regard I had hard time auditioning and most importantly defining the differences between Burson V5i and MUSES01 as they might seem on par at first but still they are not equal in reproducing various music genres. I can say that both opamps are in the same hi-end league and offer incredible sound stage and 3D presentation but each with their own sound signature. Just like everything in the music world there is no single solution for every type of music. To excel in one area means being unable to do the same in the opposite one. It's called balance.
 
I have already shared my impressions regarding Burson V5i. Hence I will present just a summary comparison table of Burson V5i vs MUSES01 below:
 
*with LT1028ACN8 buffers

Summary

 
Truly Burson V5i are amazing opamps and I will definitely put them in the hi-end league. Having the right set of headphones, capable of constructing 3D sound stage during sound reproduction is a must for these opamps.
 
Remember, the sound is as good as its weakest link in the chain. Thank you!
 
PS After another set of buffer rolling and more hours of auditioning my opinion regarding LT1028ACN8 buffers has changed. They are actually not that bad at all. I'd rather say pretty good. Was it that my brain adjusted to the sound or the opamps burned in. I have no idea but now they improved the overall presentation adding some details which LT1010 lack. Somehow they add +1 point to classic rock and acoustic guitar presentation. So far I'm keeping them with Bursons V5i:
 

*The heatsinks in the photo are my custom upgrade due to LT1028ACN8 tend to warm up.