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Operationally and connexionally making mistakes would imply criminal intent.  There’s only three high-level inputs plus a main-in to bypass the preamp stage. There are 4/8Ω speaker terminals on the back and measurement ports for output tube bias current adjustments. That’s it. So let’s fire ‘er up and delight in the first noise being a light mechanical shake as the transformers come to life. That’s in line with the heavy equipment Harley vibe and accelerates the heart beat of fanatics to suspect that it's not the trafos but a special small V-twin shaker motor. Lest this induces paranoia, let me assure you that the Evolution 845 is otherwise very quiet and hum is low. You’ll have to really crank the juice and run higher-efficiency boxes to hear any self noise in the listening seat.

That the Mastersound Evolution 845 would be a lustier elegant player rather than science nerd seems foregone conclusion. Core differentiators are a certain tonality and a certain way of depicting space. All clear? Hardly. Let’s start then with tonal balance in the bassment.

For the money asked you can buy lower, faster, more articulate resolved bass elsewhere. The last transistor amp through here was the less than half-priced Plinius 9200 with a rather drier foundation. If that’s what your doctor prescribed because half your library consists of electronica weaponized with evil synth bass rocket launchers, you’ll have problems with the MasterSound. Conversely when the money aspect is eliminated to focus solely on the technical concept—class A single-ended with minimal feedback and triodes—bass becomes surprisingly potent. It goes real low with conviction and clarity; for a SET.

To be clear then, should S.E.T. reflexively conjure up femmy vocals with light New Age piano washes, you’ve got it all wrong. For garage-born Rock of one, two, three, four, off we go caliber the MasterSound is perfectly suited. Think Dire Straits, Stones or as I did, Violent Femmes’ Live which in either case will mean that deep bass isn’t an issue (not really fully present on such fare in the first place) and that the Italian has plenty of piss, vinegar and punch. To be more specific, bass quantity—energy, impact, bass drum displacement—is plenty sufficient and if in doubt even slightly enhanced. It’s fair to talk of a juicy balance over which handmade Rock has never yet complained. How ‘bout quality though?

My first note in the black book reads "bass overall generous, juicy, not very dry but still differentiated and mobile". And so it was that on the Live classics "I Alone" and "All Over You" the Evolution 845 produced more low-down welly than my pre/power combo of Octave HP300Mk2 and Electrocompaniet AW180. While the Norwegian monos applied firmer control to be theoretically ‘righter’, the Italian injected more energy. With these neither audiophile nor excessively fat Rock numbers, the Scandinavian version felt less powerful and somewhat more abstinent/sober. The MasterSound gifted more gravitas to the e-guitar workout which I found exceptionally attractive. It also sounded more substantial.

The overall tonal balance and flavor of the midrange was clearly due to a light emphasis in the bass and a light depression in the upper midrange. This deviation from flat seemed neither sinful nor excessive but characteristic nonetheless. On Joanna Newsom’s Have One On Me I remembered her voice at particularly higher levels as more pixie-ish whilst male vocals got a boost in sonority. The Evolution 845 plays it round, full and a bit softer. Relative to certain female vocals I’ll have to retract my earlier phrasing and call it sinful after all – splendidly so too.