Disclaimer: Burson sent me a sample unit for this review. Burson is also a site sponsor.
The addition of the SL variant of the Soloist brings a more affordable of version of Burson’s 21-component FET design into the $600 price bracket. Most notable changes include the power output which has been lowered to 2W instead of the 4W of the standard issue Soloist, a more economical ALPS pot instead of Burson’s premium stepped attenuator, the abscence of pre-amp out, a two level gain stages instead of three, and finally two input channels instead of three.
On the enclosure side, the SL received some trimmings as well. Instead of the standard Soloist’s machined 6mm aluminum enclosure is a 4mm folded aluminum. Yes it’s no longer machined aluminum, but the 4mm aluminum is still far thicker than the majority of desktop amps out there. The overall finish is still premium enough for a $600 amplifier, but placing it side by side to the original Soloist, the SL looks a step lower in terms of finishing quality. I don’t really lament the drop in finishing quality. As long as I don’t have it side by side with the standard Soloist, the SL looks refined enough on its own sitting next to my Apple Cinema Display. The smaller dimension is quite welcome, again it doesn’t look as muscular to the slightly bigger original version, but I’d definitely prefer the Soloist SL’s footprint when I’m listening to music on my computer desk. With the smaller dimensions and thinner aluminum enclosure, the SL also loses quite a bit of weight, but it’s still reasonably heavy to maintain its own stance in the presence of big 1/4″ headphone connectors.
Burson told me that the circuitry is basically the same aside from the changes I mentioned above. Comparing the two amps side by side, I noticed that a lot of the difference is similar to what I observed on the Burson HA-160D and HA-160DS. The amplifier equipped with the Burson stepped attenuator (in this case the original Soloist) is a step forward in technicalities. An improvement in soundstage width, instrument separation, the definition of each notes, blacker background and lower noise floor, improved clarity across the frequency range, better bass control, and overall a shorter decay. The ALPS blue equipped Soloist SL sounds less wide (though a bit better on the depth), notes are presented more in groups instead of self-existing individuals, decays are longer, bass notes slightly longer in decay and more blurred. How big of a difference are we talking about? Small enough to consider the two still belonging to the same Soloist house sound, yet distinct enough to make me prefer one version over the other. It clearly reflects the difference in pricing: the Soloist SL is the lower end model of the same line up, yet the SL possessing enough unique qualities to separate it from the bigger brother.
It’s totally unsurprising to me that these differences may be attributed to simply a change in the volume control device. After all, that’s the first thing the input signal hits the moment it enters the amplifier. Between passing through the metal film resistor on the Burson stepped attenuator or through the resistive element on the ALPS blue potentiometer, the difference is quite audible and the same effect can also be observed through different amplifiers (for example on the two Beta22 amplifiers I built once).
Depending on my mood, I do prefer the effects the ALPS blue brought to the Soloist SL. Longer decays, overall better sense of coherence, a more relaxed stance in the overall sound, and more bloom in the midrange. Overall, there’s definitely a drop in technicalities, but musicality is still strong and perhaps even slightly better depending on what you’re listening to (i.e slower music, the more relaxed SL seems to strike a better synergy). Clearly it doesn’t sound as technically impressive as the original Soloist, but even with something like the HD650 plugged in, I never feel the Soloist SL to sound congested or small. After all, the discrete, minimal 21 parts FET stage, class-A running design of the Soloist is far from a budget level circuitry. For instance, as I was doing a review on the Fostex headphones, I was surprised to find that the Soloist SL actually does a better job at front-to-back instrument layering than the Bakoon HDA-5210mk3 amplifier. It doesn’t quite beat the Bakoon in the overall scheme of things, but the Burson definitely had something solid going on for its price tag.
The drop in power output may be something to think about, if you happen to own a Hifiman HE-6 or plan to get one in the future. For everybody else, 2WPC is plenty for everything else in the market, not only dynamics but the other orthdynamics headphones in the market. If you’re bold enough to try the HE-6 on the Soloist SL, you’ll still find that the 2WPC output is still more than adequate to drive it, provided you’re not listening classical recordings with their notoriously low mastering level. The average recordings play nicely at about 11-12 O’clock at high gain. With a sensitive headphone like the Fostex TH600 and TH900, the low gain setting provides plenty of volume control range.
The $400 drop in price between the $599 Burson Soloist SL and the $999 Burson Soloist is enticing enough, in my opinion, to bring people shopping for a $300-$400 to up their budget to $600 for the Soloist SL. After all, $300-$400 entry level desktop amps rarely have anything to brag about other than “it’s pretty good” or “it’s a good value amp”, where another $200 brings you the same solid circuitry that powers the $1K Soloist and the $1,850 Conductor. Don’t we all love it when manufacturers come out with a new product to tempt us with?