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As you should with any FirstWatt amp
, I let both warm up for a good half hour before putting live signal to them. That's because their circuits are calibrated to perform optimally once their output devices have reached thermal stability. Swapping cables without noise simply meant obeying the proper sequence: speaker cables off first followed by the ICs; and the latter on first followed by the speaker leads. The instant thing to observe was that despite deliberately sparse tonal assist upstream—transistor pre set to zero voltage gain, ultra-resolution DAC—neither one sounded bleached, pale or pinched. No, the Swiss eggs didn't sound as fulsome and pumped up as they had with the just departed Auris Audio 100-watt 6550 Forte valve monos. But they traded points on higher resolution; more bandwidth particularly on top; wirier bass; zero noise where the Serbians had suffered steady-state power supply hum in the listening seats; and more speed on the uptake of leading edges. Where the tube amps had transformed the tonewood speakers into red-cheeked thick-ankled muscular but plump working farm gals, these transistor amps suggested still muscular but more toned ladies, say ballroom dancers. They moved rather differently and with more elegance.

Compared to my 1MHz bandwidth DC-coupled Crayon Audio CFA-1.2, either F6 belonged into a warmer slightly softer class of less transient bite. Even so their reflexes as manifested in separation power for dense passages and large ensembles were closer to the Crayon, not halfway between it and the push/pull valve amps. By contrast, the silver-faced F5 of equivalent power was a bit more brash and fresh. It had more lemon zing and thus huddled still closer to the Crayon. With this general lay of the land, how did DIY and production F6 diverge?

Honing in on turns of gestalt is easiest when albums play to them. If you don't know what to listen for, it could take a few trials until you chance upon a cut that shows off a key difference. Once its mark is made, you detect it elsewhere too. Going through two which first left me none the wiser, the third album was a hit, the next a logical confirmation. Enter Rafael Cortés' Cagiñi and Juan Carmona's 24/96 Alchemya: two masters of the Flamenco guitar, one with an essentially solo track, the other with an accompanied guitar duet.

With the first's more close-mic'd string action, the second's more ambient mix sporting two guitars with slightly dissimilar tonalities, it was clear how the SemiSouth part by contrast was glassier. It emphasized more metallic string elements and invoked less Spruce wood response of the guitar bodies. It felt quite as though one played with a tripod-mounted macro lens and deliberately manipulated its depth of field. For the DIY F6, extreme lens lock was most directly on the strings, hence the wood behind them was already blurred. For the production F6, the focus was solidly on the wood grain whilst the strings themselves were less sharply rendered. If you can transfer that camera visual to sonics, voilà!

As a consequence of this minor reweighting between attack and bloom, the Mosfet part felt more suave and elegant, the JFet less rich but more crisp and jumpy. Entering this attempt at differentiation with a reverb-laden production of wood winds and vocals for far more legato than staccato and in general less ripped percussive striations, one would be less likely to pick this out. Well-captured close-up piano meanwhile proved very telling. So did violins particularly where played 'dirty' in Mideastern modal style or with much flageolet à la Russian gypsy fiddlers.

Likely a function of primarily a different distribution of remaining harmonic distortion elements, a related subtle effect occurred in the depth domain. On recordings with well-developed venue depth, the slightly sharper more incisive SemiSouth part separated out more ambient data. The minorly fatter richer Mosfet parts gave more solidity to the foreground performers and a bit less 'thru-sight' into the stage rear. Listeners coming from typically warm valve amps would find a bit more overlap with the production F6. One senses more connective tissue between the notes as though space had become heavier. The power JFets played it more lucid and lit up. Transparency clicked up a notch, subjective mass slid down by one. This game was quite minor. The more one tracks it, the more obvious it gets during embroiled A/Bs. Then one settles down with one or the other, hearing acclimates in a hurry as it always does and one duly forgets about the whole thing.

At this juncture curiosity got the better of me. Rather than swap speakers, I first swapped amps once more to take the measure on single-ended no-feedback SIT2 vs. push-pull feedback F6. As soundkaos designer Martin Gateley shared, he too has observed that his Wave 40 responds with appreciation to more power. That's despite nominally sitting in the efficient widebander class which typically gets associated with micro-power SETs. Just because such amps can't drive much else doesn't by necessity imply that such speakers will sound best with them. Here we must add that on raw voltage conversion effectiveness, ~93dB is a far cry from the 100dB+ league of Lowthers, Rethms, Voxativs and horns. A number of otherwise perfectly conventional dynamic speakers like Magico or Wilson today can hit 94dB. Few would chose puny 10-watt amps for their multi-ways primarily because their crossovers are reactive and their bass systems current hungry. Though a simple two-way, the Wave 40 does separate its drivers with dedicated hi/lo pass filters to cut out the widebander's final reach where its response gets ragged. In short, it's not a typical zero-filter widebander. Just so my treasured pair of SIT1 has been my favoured artillery for them and I normally use Zu's Submission subwoofer to fill out their response below 40Hz. With that scene set, what were the results?

Whilst texturally a shoo-in, the SIT-2 soundstaged very differently. In our new larger space since the Villeneuve flat where many previous FirstWatt outings had taken place, the static induction transistors now cast a decisively wider and deeper stage. Everything was plainly bigger particularly laterally but also backwards. Within that grander panorama, the contrast ratio or virtual presence limning of individual performers also was higher by a surprisingly pronounced extent. The ability to walk into the action with my mind's eye—not its windmills!—and inspect whatever specifics I fancied was flatly greater. Vis-à-vis the siblings, said SITuation hadn't telegraphed to the same extent in our former digs. In our rather larger space it now had become overt and of a tacit instantly self-validating sort. Hearing it wasn't the issue; describing it accurately more so.

Presence limning actually does seem like the best term. Here's the extended version. Most of us are all too familiar with the phenomenon of outline sharpness. It usually applies to quite two-dimensional shadow-play profiles. They simply get more backlit to exhibit crisper edges as this quality or attribute improves. With SIT insertion, said effect applied itself in rather more totalitarian fashion. If usually the virtual performers are only partially extricated from the background—no longer scissor-cut flats but certainly far from fully rendered phantoms one could walk around and check out from the back—this felt far closer to full-on freestanding separation. The outline clarity whereby one virtual source stands distinct from others occurred in far more three- than two-dimensional space. That in a nutshell, was the SIT2's quasi holographic advantage. That its bass wasn't as grippy as the F6's didn't even matter. All my attention was on the big deal of spatial expansion and heightened contrast without any added bite to make it so. Twice-plus the power (six times into 4 ohms) didn't really factor for the F6 where these speakers were concerned. Sometimes power is decisive. Sometimes it's not. For my Aptica towers, it would be. Here the SIT2 or SIT1 are underpowered to collapse in the bass and get a bit lean overall. There I would be down to swapping between F5 and the two F6 variants.