First off, I’d like to thank Burson for sending me a V5i Op-amp to test in my walnut F1 and other devices. As a matter of chance, I also received the Play test unit with the V6 Classic and V6 Vivid Op-amps so have had the opportunity to compare and contrast all three against the other common op-amps on the market.
This has probably been the most difficult review I have done to date. Changes between op-amps are not something that just jumps out at you and makes for easy comparisons. At best, changes are incremental and at worst, differences are so small that at times I questioned whether I was hearing a difference or was grasping at straws.
For purposes of this review, I used each op-amp in a variety of gear so as not to assume any characteristic of one amp or another was actually an effect of the op-amp swap. On the portable side, I tried the op-amps in the Zishan DSD, the Walnut F1 amp, and the Fiio E12 DIY. On the desktop side, I used the Little Dot 1+, and a Topping T30. I stuck with devices that use a dual op-amp in order not to introduce any variability due to that so all references from here forward are to the Dual version of the Burson products.
For those of you who might not have replaced an op-amps before, it is worth noting that installing an op-amp backwards is physically possible but will more than likely result in burning out the op-amp and quite possibly the device you install it in. Be very careful to know where pin 1 is on both the op-amp and the socket and align them properly. My advice is photograph the existing op-amp before removing it with enough visual cues around it to be able to re-install it using the same orientation. Having this reference will save you later, trust me. Most op-amps have a marker at one end in the form of a half circle cutout in the edge of the chip as shown below. Others may not so be careful.
Also, worth noting, just because an op-amp will fit in the socket does not mean it will work properly. Electrically, op-amps vary and are rated for different rail voltages and differing input current. In most cases, differences are not enough to result in damage to the device around the op-amp, but it is a possibility. Running an op-amp outside of spec can make for worse sounding output. Remember, just because an op-amp sounds different does not mean it is an improvement and from a circuitry perspective it may well be a distinct downgrade.
I had spent a fair amount of time rolling op-amps in the walnut f1 looking at what various op-amps might have to offer. Depending on which side you believe, I was either wasting my time entirely, or I was going to find out that the differences were startling. Truth is somewhere in between. I never had an “OMG” moment where one op-amp was just monumental different than the other, but I did find places where differences were evident. One of the differences for example is the 2134 that came with the F1 does not image as well as the 2604. Soundstage also seems narrower on the 2134 compared to some other flavors. If the imaging is better on the 2604, the detail and clarity are better on the 2134 so even though differences exist, I cannot declare a clear winner as both have pluses and minuses.
The same held true across all the op-amps I tried. A little better here, a little worse there. I ultimately settled on the Muses02 as I listen to a lot of vocal and acoustic music and this seemed like the best trade-off for me. Your tastes may vary, please do not send me hate mail about how could I pick this over that.
It is against this backdrop, that I received the Burson op-amps. Two are fully discrete, one is partially discrete. Two won’t fit in the same space as an IC and one might. I say that as the V5i would fit in some devices and allow the case to close, but not in others. The Topping and Little dot both closed, the F1, E12, and Zishan all required leaving the case off or the battery outside the case in order to fit the v5i. The Discrete V6 op-amps would not fit in any of the devices with the case in place (it was really close in the little dot but still too tight for comfort).
I listened to the same songs over and over and over with each Burson op-amp and compared against the Muses, 2604, and 2134 looking for any differences in detail resolution, staging, imaging, clarity, extension, and background. Again, differences were not gigantic, but they were there.
The v5i semi-discrete op-amp in the walnut did have one immediately noteworthy difference. It is louder at the same setting compared to any of the IC designs. This throws another wrinkle into the testing as we all know a louder sample is usually perceived as a more detailed sample. I did my best to volume match the samples so I could judge fairly. At the end of my testing, I found that it really depended on genre as to which Op-amp I preferred. The stock 2134 was closer to neutral and was technically very good. The muses brought a touch more musical presentation and was less clinical sounding than the 2134. Vocals are farther forward on the Muses which makes it an excellent choice for music where the primary element is vocals (I dig me some Pentatonix). The v5i brought a bit more energy to the presentation but seemed to be less neutral in doing so. Sub-bass is forward of midbass and upper mids and lower treble are the other focal point making for a more lively if slightly less technically correct presentation. If the muses shines with Vocals, the v5i is made for electric guitars. The place where the v5i was truly fantastic was on classic rock where it brought you into the concert and made you feel like you are sitting on the front row. Soundstage was a bit wider on the Muses but depth was about equal and extension was a split decision. At the low end, the v5i did a better job but on the other end of the spectrum the Muses had more air and sparkle to its presentation. I could live with either the v5i or the Muses, but in my case the fit inside of portable amps and the genre’s I prefer again left me in a split decision. Ultimately, I left the Muses in the Walnut F1, and put the V5i in the Zishan DSD. When paired together, I get the best of both worlds.
Moving on to the V6 discrete op amps, again I found no clear winner in all categories, but did find that the V6 op-amps did acquit themselves quite well and were an easier overall pick at the end of the testing. While both the v6 classic and V6 vivid are fully discrete op-amps, they are not the same circuitry. What is funny is the v6 Classic is not the circuit that is an evolution of the V5. That honor belongs to the Vivid. If you’ve had the opportunity to listen to the v5 and liked it, you will most likely like the Vivid as well. It is very similar to the v5i, very dynamic and energetic, if not technically absolutely correct. I found the Vivid to perform well with the same genres as the v5i, classic rock, blues rock, and blues in particular. When we got to the crooners and the jazz tracks, the extra energy is not as appreciated and I found myself liking the V6 Classic a bit better. Soundstage on the Classic is not as broad as the Vivid, but the classic provides a more intimate picture and makes it easy to see the insturuments in space in small ensemble pieces. Both the Vivid and Classic image well, but again I think the classic is slightly better. Instrument separation on the other hand is a bit more pronounced on the Vivid. I found a lot of similarities between the Muses02 and the classic as both do their best work in similar genre and both have a rather intimate staging that isn’t present on the v5i or Vivid. Detail presentation is good across all the Burson products and is probably at its best on the Vivid. Overall, if I had to pick a single op-amp and live with it, I would take the Vivid. Since I don’t have to live with just one, I’ll use the Vivid for Blues rock in the Topping and the Classic in the Little Dot where the Mullard tubes add a fluidity to Jazz that complements the Classic and really makes for a wonderful intimate performance.