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  1. AthenaZephyrian
    Gemtune APPJ: an affordable, brilliant tube amp
    Written by AthenaZephyrian
    Published Sep 9, 2018
    4.5/5,
    Pros - Great sound, very spacious and clear, compatible with many headphones, good looks
    Cons - Stock tubes are boring, and a slight hiss occurs at high volume.
    The Gemtune (string of numbers) is a nice, sleek, "made by apple"-looking tube amp. It's classy, and produces a classy sound. It needs some tube rolling to sound its best, but it's beautiful.

    I acquired this amp from a friend, to customize and send back. We plan to steampunk it, and fiddle with circuitry a bit to produce a warmer, tubier sound.

    Aesthetics and build: solid construction, nice aesthetics, a bit modern for my taste--hence steampunking! It doesn't lose any point here, though, because it's an agreeable aesthetic most would like.

    Rolling capability: This amp rolls well, though I've only had the opportunity to change one tube so far, to excellent effect. I replaces the 6N4 with an RCA 12AT7 tube from an antique philco radio, and the soundstage and imaging exploded into a huge, out-of-your-head space. I imagine replacing the cheapo chinese power tubes will have similarly excellent results, as the stock tubes are really bland.

    Sound: Easily outclasses my modified Little Dot I+ (LME49720NA op-amp, Voskhod 6ZH1P-EV tubes), with a better soundstage, and more speaker-like presentation on my HE400i's. It blows the stock amp in the SMSL M6 out of the water in every regard. It is somewhat tubey, but retains transparency well. Using the high gain switch with low-impedance cans is a bad idea, but the way; it's meant for impedance matching, and switches from very low impedance to very very high impedance, suitable for HD650's.

    Capable of defined transients and good detail on rock tracks, produces a wide "stadium" sound (especially with 12AT7), provides gorgeous vocals....there's little I can complain about, and am excited to switch out the power tubes, to see how awesome it can sound.

    With my ATH-MSR7's, the cans sound a bit surprisingly bright, but on further inspection, sound pleasantly warm with some brightness--yes, that's possible--in a very nice way, that emphasizes vocal range an "colorful" instruments like synths and guitar solos.

    My only gripe is that the stock tubes are cheap and sound bland.