The FirstWatt catalogue specializes in lower-power models with often SET-reminscent output impedances. Most of its circuits are simple 2-stage affairs whilst my SIT-1 monos pursue simplicity to its most extreme state as uni-stage circuits with zero feedback and zero degeneration. They are actually 'purer' than the very simplest of single-ended triode amps. At minimum, those must add a driver stage and an output transformer. With greater complexity and more gain stages come higher-order harmonic distortion products. Higher power also relies on paralleled, and sometimes massively so, output devices. This could mean specific addresses to linearize and stabilize their behaviour as a group. They're supposed to act as one; or as one phase in a push/pull array. Chances are that a mushrooming of devices is accompanied by higher corrective feedback. Benefits of scaling up small amplifier circuits aren't merely about higher power per se. It's about greater load invariability into challenging low impedances. There's also greater current delivery to sustain LF transient peaks; and lower output impedance for better woofer control. Just like a carpenter will adjust the size and weight of his hammer to the diameter and length of the nail and density of the material he means to penetrate, so a listener must match the amp to the needs of the speakers. A big multi-way speaker with manly woofers will likely give a far snappier salute with a muscle amp even if a lightweight specimen can play plenty loud. But going loud enough is not the same as enjoying maximized dynamic contrast, general control and proper woofer damping in particular.


With the 25/50wpc into 8/4Ω FirstWatt F5 and F6 models, I'd have two push/pull amps of very similar paper power on hand, albeit of less ambitious drive and grunt. Their limits are predicated upon FirstWatt's deliberate restriction to a fixed chassis and heat sink combination which limit power dissipation; and a fixed-size power supply which limits achievable rail voltages. With the XA30.8's different design DNA but equivalent ratings, I'd be in a good position to compare even Steven as Steven as reasonable and sample different performance flavours from the same designer. For more tech poop, here's how the press release on the Point.8 series put it. "Inspired by the Pass Labs X.5 Series amplifiers from 2006, the output stages of the larger Point.8 Series have been designed to bias more deeply into the Class-A operating region. They feature large push-pull Class-A operating envelopes for low distortion and good loudspeaker control at ordinary listening levels. The Class-A amps employ higher power Toshiba Mosfets (metal-oxide semiconductor field-effect transistors) than earlier amps. Those in the Point.8 Series run at a fraction of their stated specs. The company also installed many more Mosfets than usual on most Point.8 models. Pass Labs also improved the front ends which house the input and voltage gain stages. Each of the nine Point.8 models has a front end uniquely molded to the specifics of its output stage so that the nine front ends vary in size, voltage, bias current, dissipation and the distribution of single-ended vs. push-pull bias.


"The improvements yield direct-coupled (DC) front ends that boast very high stability, low distortion, low noise, 100kHz open-loop bandwidths and high input impedances. The power supplies are also larger than those of earlier amplifiers with a third more storage capacitance as well as new CRC (capacitor-resistor-capacitor) filtering. The power supplies still use paralleled fast/soft rectifiers and large toroidal transformers from Plitron but the AC primary circuits now incorporate additional RF filtering. Power on/off switching and a stand-by draw are also new. In addition, Pass Labs improved the output noise by more than 10dB and made the amplifiers much more resistant to variations in the AC power line. The smaller Point.8 models also feature new and larger heat sinks to lower distortion and dissipate the energy of the larger bias currents."


When I commissioned my Kaivalya EL84 push/pull monos from Trafomatic Audio's resourceful Sasa Cokic, I distinctly remember how much time he spent on mating its single-ended triode input stage to the push/pull pentode output stage through a complex interstage coupling/phase-splitting transformer with a very specific (low) amount of negative feedback embedded. Tweaking the THD behaviour and interaction of and between these dissimilar stages was of paramount importance. From what we've already learnt about the XA30.8, the same applies to its architecture. Anyone can fire up a scope and take distortion measurements with the assumption that lower must be better. It takes far more experience and critical listening to understand how harmonic distortion flavours the sound; how multi-stage arrays affect it; and what precise distribution of 2nd vs. 3rd-order behaviour is most attractive for a given circuit (and how it perhaps ought to shift with increasing vs. decreasing power levels).


Here we remember Nelson's comment that in the olden days—which is to say, before computer simulations and the latest-gen test gear—hifi designers had to rely far more on listening than they do today. Advances in measuring and modeling kit allow for many shortcuts in the 21st century. As Halcro claimed to have done, this might even break new records for vanishingly low distortion levels at the edge of our ability to measure. Yet as Halcro have also shown, such a feat needn't equate to attractive involving sound. At Pass Labs, listening between trusted members of a panel plays a big role to guide their final designs. As their site puts it, "oscilloscopes and distortion analyzers are excellent tools but they historically make lousy customers. Our real customers care most about the experience they get when they sit down to listen to their music."

So much for setting the stage of my informal family meet between two FirstWatt and one Pass Labs stereo amplifier. One thing was certain. Unlike with real family get-togethers during the holidays, there'd be no squabbling. Obviously I'd not have the kind of truly 'manly' speaker loads the XA30.8 was designed for. My assortment of speakers—soundkaos Wave 40, Boenicke Audio W5se, Albedo Audio Aptica, German Physiks HRS-120—respond well to the gentler charms of the FirstWatt amps. Would this pre-rig the game in their favour? Or had I gotten used to a certain sound; perhaps even adjusted my listening habits to compensate for certain losses or weaknesses which the Pass Labs amp would now reveal? Only one way to find out.