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Apogee Symphony I/O MkII 2x6SE

Thunderbolt Audio Interface By Sam Inglis
Published October 2018

Apogee Symphony I/O MkII 2x6SE front panel.

Apogee increase the range of their Symphony I/O MkII interface with a module aimed squarely at mastering.

Manufacturers nowadays seem to spend a lot of time ‘refreshing’ their product ranges, and two years ago Apogee gave their flagship Symphony I/O a particularly vigorous spritz with the iced water. The Symphony I/O MkII is still a modular audio interface and A‑D/D‑A converter, and can still house some of the same I/O modules; but it now offers low‑latency Thunderbolt connectivity and very different cosmetics, with a large and friendly colour touchscreen.

You 2x6SE Things

When I reviewed it back in SOS September 2016, the MkII was accompanied by two then‑new I/O modules. The 16x16 MkII provides 16 channels of line‑level analogue input and output, and the 8x8 MkII eight analogue and eight digital inputs and outputs; and, having used them, I could find no grounds to dispute Apogee’s claim that they offered the best conversion of any Thunderbolt interface on the market.

However, Apogee now claim to have raised the bar even further with a new Symphony I/O MkII module called the 2x6SE. Targeted squarely at mastering engineers, it has incredibly good audio specifications: its stereo analogue inputs are claimed to offer a real‑world dynamic range of 124dB, with THD+Noise as low as ‑116dB, while the six analogue outputs perform even better, with 131dB dynamic range and THD+N measuring ‑118dB. Both have a frequency response that is flat to within ±0.05dB from DC upwards; and if, for some reason, you don’t want to use Apogee’s converters, you can also take advantage of built‑in stereo AES3, coaxial S/PDIF and optical digital I/O (word clock is built into the Symphony I/O chassis).

The analogue inputs are on XLR connectors, but all six analogue outputs emerge on a D‑Sub connector wired to the usual Tascam format, and the host unit’s built‑in monitor control can be made to wield authority over them in several different configurations. For example, if you choose the ‘2 Speaker Sets’ preset, then physical outputs 1/2 and 3/4 will both receive the same stereo output stream from the computer, with features such as speaker switching and volume control available from the front‑panel touchscreen, while physical outputs 5/6 appear as separate routing destinations in your DAW, bypassing the volume control and so forth. Alternatively, all six outputs can be ganged together for 5.1 monitoring, or the built‑in monitor control can be bypassed completely by setting them all to ‘line’. With comprehensive trim and calibration options for each input and output, it should be straightforward to integrate the 2x6SE into most mastering studio setups.

The 2x6SE is available as an expansion module for existing Symphony systems, and you can also buy a complete system comprising the chassis and the card pre‑installed, which is how the review system arrived. Either way, though, Apogee don’t supply a Thunderbolt cable, which is pretty disappointing in a product costing this much.

The 2x6SE is equipped with two analogue inputs on XLR sockets, a D‑Sub connector for the six analogue outputs, AES I/O on XLR sockets and optical connections for ADAT, SMUX and S/PDIF. Thunderbolt and Word Clock ports are mounted on the Symphony I/O MkII’s chassis.The 2x6SE is equipped with two analogue inputs on XLR sockets, a D‑Sub connector for the six analogue outputs, AES I/O on XLR sockets and optical connections for ADAT, SMUX and S/PDIF. Thunderbolt and Word Clock ports are mounted on the Symphony I/O MkII’s chassis.

Playing Out

In order to give the 2x6SE a proper workout in its natural habitat, I took it to visit mastering engineer and SOS contributor Eric James, who trades under the name Philosopher’s Barn Mastering. To say that Eric takes audio quality seriously is something of an understatement, and his current setup involves a D‑02 converter and C‑03 preamp from Esoteric — the high‑end division of TEAC — feeding a huge pair of floor‑mounted active ATC SCM50 ASL monitors. Given that the current version of the D‑02 alone retails at around £16,000, this is pretty close to the state of the art and, unsurprisingly, the system as a whole sounds jaw‑droppingly good.

For our comparisons, we played all the material from iTunes on my Macbook, feeding the D‑02 from the 2x6SE’s AES3 output. The analogue outputs from the D‑02 and the first pair of 2x6SE analogue outputs were then fed into separate inputs on the C‑03 preamp and carefully level‑matched on the C‑03.

Eric has worked his way through numerous other D‑A converters in the course of his mastering career, and says that since buying the D‑02, he now finds some of the older models unnaturally bright. That certainly wasn’t the case with the Apogee, which held up very well even in such exalted company. Nevertheless, there were audible differences between the two, which were perhaps most apparent at the low end; whereas the D‑02 presented a completely effortless, fast and natural bass, the Apogee seemed slightly weightier and perhaps not quite so nimble. Further up the spectrum, what was most impressive about the D‑02 was its ability to put across mid‑range detail without adding any artificial sparkle; the Apogee, too, was detailed, but possibly a shade less so, and a hair more forward.

On some material, Eric felt that the differences were significant enough that they might cause him to make different decisions in the mastering process. Nevertheless, I think both of us were impressed by the 2x6SE. Its presentation of audio through Eric’s system was not identical to that of the D‑02, but it was very good in its own right, and undoubtedly of ‘mastering grade’, whatever that means. In light of the enormous price difference between the two, the subjective performance of the Apogee was excellent, especially when you consider that D‑A conversion is only one aspect of the Symphony I/O’s multi‑faceted skill set.

Having spent a happy couple of hours A/B’ing the 2x6SE with the D‑02, we decided it would be only fair to compare it with something closer to its own pay grade, namely Eric’s DACS Clarity monitor controller, which incorporates a Crookwood D‑A converter (this is normally used only as a headphone amp in Eric’s setup). Here, too, there were audible differences. Again, the Apogee seemed weightier in the ‘upper bass’ area; sometimes this made the DACS sound bass‑light by comparison, while on other material it allowed the lower mid‑range to come through more effectively on the DACS. Comparing Eric’s vinyl original of Television’s Marquee Moon with the 2003 remaster was particularly illuminating, especially in regard to Fred Smith’s bass guitar. This came across as gloriously throaty yet full on the vinyl; the throatiness was still largely present on the remaster through the DACS, but the fullness was missing, while the Apogee tipped the balance slightly the other way. The Apogee was clearly superior in the upper mids, rendering vocal sibilants very faithfully while the DACS showed a tendency to grittiness.

The Master Game

In a world where more and more mix engineers are switching to all‑digital ‘in the box’ operation, mastering remains the last hold‑out of high‑end analogue. The 2x6SE offers sufficient features and I/O to cater for most typical analogue mastering setups, and implements them without any compromise on quality. For instance, you could use its six outputs and two inputs to connect two pairs of loudspeakers and an analogue processing chain, with a separate digital outboard chain connected via AES3; and if you prefer to use an outboard monitor controller, you can defeat the Symphony’s monitor control and have it output a ‘pure’ line‑level signal at your chosen calibration level. With the host unit providing word clock I/O and a better‑than‑decent headphone amp into the bargain, not to mention the option of adding a second I/O module further down the line, it makes a versatile centrepiece for almost any mastering studio.  

At The Controls

Apogee Symphony Control software.

When the Symphony I/O MkII was launched, it shipped with the Maestro control‑panel utility familiar from previous generations of Apogee interfaces. This looked and felt like a relic of Mac OS 9, and using it to control a high‑spec Thunderbolt interface was a bit like driving a steam train on High Speed One. So, unless you’re a metaphorical steam‑train enthusiast, you’ll be pleased to learn that Maestro has now been replaced by a new utility called Symphony Control.

This is, as far as I can see, identical to the Element Control utility bundled with Apogee’s more affordable Elements range, which was reviewed in SOS April 2017, so I’ll refer readers to that review for a detailed account. Symphony Control is bang on‑trend in terms of user interface design, which is to say that it is dark grey throughout, with black highlights. Various aspects of the Symphony and its I/O cards are accessed by clicking on rather cryptic icons; both text and icons are rather on the small side for my tastes, and although the window can be resized, individual elements remain resolutely teeny.

Once you’ve turned up the brightness and familiarised yourself with some of the more abstract grey‑on‑grey icons, however, Symphony Control proves straightforward to use, at least with a relatively basic I/O configuration such as is found on the 2x6SE; and, in any case, nearly everything under its control is also adjustable from the front panel of the Symphony.


  • Audio specifications that are hard to match at any price, and excellent subjective sound quality.
  • Offers a well-judged range of analogue and digital I/O for mastering duties, with plenty of configuration and calibration options, plus a monitor control that can be bypassed if you need to.
  • New Symphony Control software is a big improvement over the older Maestro utility.


  • Some zoom and colour options for Symphony Control would be nice.
  • No Thunderbolt cable supplied.


The 2x6SE card makes Apogee’s Symphony MkII system an attractive option for mastering engineers seeking a flexible, good-sounding and relatively affordable hub for their setups.


£2429 including VAT.

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