If all this preamble was more blanket coverage than specific, it helped to differentiate the line from the rest of the Yamaha integrated pack as well as put the A-S2100 in perspective within that group. The middle child of our Mosfet trio has a lot to offer. It has a generous heaping of the big brother's attractive features and some higher grade touches that put it above its junior sibling. With tone controls bypassed, the A-S2100 circuit is fully discrete and utilizes thick cable and screw clamp connections between the pre and amplifier stages for superior signal transmission. The headphone stage gets the trickle-down upgrade of a discrete circuit as opposed to the IC design of the A-S1100. On paper the A-S2100 is very well endowed for its price, with detail work that could potentially translate into serious performance.

Although there is a lot of technical innovation under the hood, Yamaha have chosen to remain classic with their cosmetic styling's elegant touches. On the front is a ¼" milled aluminium faceplate in brush finish, available in silver or black. Side panels are real wood finished in piano black (and yes, this is real piano black done in their piano factory!). Control knobs and selectors are solid aluminium. The oversized finger-contoured speaker terminals are cut from solid brass and gold plated, with a partial shroud to prevent accidental shorting. The large attractive frontal meters scream old school but there's a lot of modernity behind the scenes. Backlighting is soft tone LED chosen to honour heritage but with a much longer lifespan. The meters are selectable between Peak and VU display as well as 'off' for those who prefer their front panel unobtrusive. The silky volume pot has the perfect feel but actually swings a digital resistor ladder. The gold-plated switch selector operates as a relay with corresponding LED lights for each source to make selections easily identifiable. The tone and balance controls look classic but centre position in their range removes them completely from the circuit. It is similar in philosophy to the Pure Direct option on the A-S801 integrated but with more flexibility. Again, the looks are classic but the engineering is modern.

The phono stage has selectable MM and MC via toggle. To the immediate right is a mute toggle switch. The speaker switch has the traditional options of A, B, A+B (also designated as bi-wiring) and 'off'. The caveat with using two pairs of speakers is the requirement that the impedance of the speakers be 8Ω minimum each. There is also a versatile fully discrete headphone stage with a full-size phono jack on the left front panel, serviced by a trim pot to match the requirements of a wide variety of loads. On the lower left is a power toggle switch which allows full off, standby and on. The supplied remote matches the aesthetics of the unit with an elegant aluminium finish on the top plate and black bottom. It is intended as a multifunction device to also serve the matching CD 2100 and/or a tuner. The layout is simple and intuitive and the raised control surfaces, sizes and groupings make it easy to operate in low-light situations. The volume control is extremely quick to respond, so gentle taps rather than hold and wait are required.

The rear panel is a combination of conventional connectivity done with quality execution plus a few unusual wrinkles. Befitting the balanced protocol, there is a pair of female Neutrik input XLR. Grouped in that area are two small toggle switches. One is an attenuation switch selectable between bypass and -6dB to match signal levels between balanced and non-balanced input sources as well as correcting for potential signal overload arising from components with unusually high output levels. The other is a phase switch which gives you the option of normal/inverted to guarantee absolute phase with differing source products. On the opposite side of the back panel is a simple on/off slider to activate an auto power standby feature, which automatically kicks the power down to off if the integrated has been left on without signal for 8 hours.

With the exception of the single pair of XLR, the rest of the inputs are RCA and dubbed legacy Line, CD, Tuner and Phono (with a grounding post) plus Record in and out. The Pre out and Main In loop allows mix 'n' match with different preamp or amplifier combinations. Choosing the Main In option disables the preamplifier functions. There are also smaller input jacks for trigger and remote in/out functions to connect external components that can make use of these features. Speaker connectivity is via two pairs of massive finger-contoured binding posts selectable for single pair, biwire or multi speaker capability chosen via front panel selector. Listening sessions were conducted using a number of different combinations. The first set was conducted with the Apogee Acoustics Duetta Signatures running full range with the Arkana Physical Research interconnects in single-ended configuration plus the Wyred4Sound DAC-2 and fellow Music Server doing duty as source for both stored musical files and Tidal streaming. Since Yamaha's own companion CD-S2100 is based around an internal ESS Sabre DAC, I decided to keep the Wyred DAC as mainstay to closely match the designer's performance intentions. Google's Chromecast audio also got a kick at digital streaming to explore how it fared on the budget end with Tidal. Results were respectable but not on the level of the Wyred alternative. Chromecast quality also varied with operating system. Between Apple and Microsoft, the Apple iPad route proved somewhat problematic and sonically challenged versus a Windows 10 based laptop, which was clearly superior. Since both are software driven, I assume all that could change.

During this round, the thick stock 2-prong Yamaha power cable was replaced with the Arkana Grey for a brief period to see what the differences would be. Although there were changes, not all of them constituted improvements. In the end I stuck with the stock cable since again, it adhered to the intentions of the designer. The question of break-in came into the picture. The recommendation from the distributor was a few hundred hours which proved accurate. The A-S2100 sounded more than respectable straight out of the box but improved with age. It increasingly gained authority in the bottom end and became more effortless and spacious in its handling of dynamics and soundstage respectively over the listening period.

The second round went to evaluating Yamaha's attempt to sidestep the balanced vs. single-ended debate. Here I ran a parallel feed of Audio Art IC-3SE Cable, one terminated with Sound Connections Xhadow XLR connectors, the other with the Xhadow RCA. In this test, full-fledged balanced emerged the victor. Both setups maintained frequency character but diverged in transient attack, where the XLR mustered greater responsiveness and thereby superior resolution and dynamic complexity. The converted single ended path rounded the edges a little bit, robbing the performance of a small amount of detail and life. The limitation was quite subtle and only noticeable by direct comparison. Standard RCA remained exceptionally revealing in its own right. My third round replaced the Apogee Duetta Signatures with an incoming set of potential powerhouse monitors, the Clearwave Audio Design Resolution BE. This presented the Yamaha with an entirely new set of challenges. This small wide-bandwidth loudspeaker has a low 85dB efficiency with a reputedly stable 4Ω behaviour and according to Clearwave should plumb bass into the low 40s with its 6½" ScanSpeak mid/woofer when coupled to an amplifier of sufficient intestinal fortitude. It also sports a ScanSpeak Beryllium tweeter which by reputation parades a hyper level of detail. If mishandled, this pairing had all the potential of a nasty dichotomy of bass mush and treble rawness. Would the A-S2100 remain suave and sophisticated or fall apart?

The answer turned out to be the happier option. The Yamaha relished the assignment. The combination of low sensitivity and lower impedance didn't prove problematic and the pairing was in fact robust, lush and lively. Achievable volumes and dynamics were quite impressive and the combo displayed the ability to energize the room and house with musical gusto, power and finesse down to 30Hz. A fourth setup connected the Wyred4Sound DAC-2 to the Main In, bypassing the preamp stage to allow me to hear the character of the amplifier on its own and by virtue of its absence, interpret the contribution of the preamp stage. The Audio Arts single-ended interconnects remained to keep the experiment on consistent ground. Feeding the amplifier direct revealed a very rich tonal balance, weighted into the midrange through upper bass spectrum in almost classic British speaker style with a slightly soft but highly detailed top end. The soundstage was massive and airy but also mildly diffuse as was instrumental positioning, with emphasis on density and scale over transparency. By process of elimination, the preamp stage of the A-S2100 appears to sharpen focus of positioning, projection, depth and hall cues without compromising overall soundstage dimension. The pair operated as a "hand in glove" match, complementing strengths and eliminating weaknesses. While one can experiment with mix and match combinations on the separate stages of the A-S2100, it will be difficult to outperform the designer's finished achievement.