PS Audio Sprout100 Integrated Amplifier

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In February of 2015, I reviewed the original PS Audio Sprout, the brainchild of Scott McGowan. It was a powerful, small, simple to use stereo integrated amplifier with DAC, analog preamplifier, headphone amp, phono stage, Bluetooth receiver and more; I was dazzled by its performance at $799. Now we step forward 3 years to the second generation for review here: the Sprout100—at only $599.

I ran into McGowan recently at the Rocky Mountain Audio Fest in October 2017, where he pulled out a prototype of the Sprout100 from his backpack at the hotel restaurant for my perusal; my eyes lit up at what I saw—and hoped to hear soon after. As I will try to convey in this review, some serious thought by McGowan was clearly given to this new version, and by drawing upon the expertise of PS Audio’s engineer Darren Myers, PS Audio has produced a product of exceptional value—and substantially better than the original. 

What's New?

The dimensions and weight of the Sprout100 are essentially the same as for the original Sprout, 1.9” (H) x 6.2” (W) x 8.2”(D); 2.9 lbs., and the minimalist looks are very much the same, but technical changes abound; a serious rebuild/redesign was implemented throughout. Why the ‘100’ in the name Sprout100? Because its amp outputs 100W per channel 4 Ohms, 50W per channel 8 Ohms (versus about half that in the original). That is certainly a serious change, and the sides of the unit now have grills as do the bottom to facilitate cooling. Here are other changes:

        • It is endowed with a new and better DAC chip: the ESS Sabre 9016 (versus a Wolfson WM8524).

        • It can now play DSD and do so up to double rate (128), and PCM now up to 24/384 (original was only up to 24/192). The new DAC chip also increases the quality of the Bluetooth mode because as before the Bluetooth implementation it uses pulls the raw data from the Bluetooth module and passes it directly to Sprout’s DAC chip.

        • It now has line level RCA for analog input (it always had that for vinyl, but otherwise one 3.5mm input, and one 3.5mm output).

        • It has a dedicated separate output for a subwoofer (one had to use the 3.5mm analog output before).

        • In addition to USB, it has an optical (TOSLINK) digital input instead of the coaxial one that was in the original. This can be used to input many other things such as a TV, etc.

        • It has a redesigned RIAA phono stage (the phono stage is meant for moving magnet only, with loading at 47K Ohms, 100pF)

        • It has a redesigned headphone amplifier with double the output as the old (now it is 32 Ohms: 500mW; 300 Ohms: 125mW).

        • It now has a well-made brushed aluminum remote control (optional to use) for on/off, volume and mute (a new feature)–I keep it on the door of my metal refrigerator when not using it;  explanation later.

        • It no longer has a power switch on the back; one can power the unit on/off using the volume knob (press it), or using the remote.

        • The power knob is now an infinity knob, it keeps turning, and is solidly made. Makes for selecting finer volume levels and for allowing use of the remote.

        • It now has a universal internal power supply; you can use it internationally without worrying about voltage. (As before, the power plug on the back allows you to use your own power cord.)

        • A bass-booster mode (filter) can be enabled or disabled; it ramps up bass if you so wish when you have speakers attached, not headphones, and gets automatically turned off if you attach a subwoofer. (I found that I always keep it disabled; sufficient bass is realized with the new 100W per channel. But, perhaps at low volumes it can be useful.)

        • It has lower THD, < 0.01%; less than half of that from the original, and higher Signal to Noise; > 105dB (versus > 90dB in the original).

        • It now has an LED indicator light (above the volume knob) so you know if it is powered on/off or muted; if the bass booster is enabled, then it shines white, blue otherwise and when muted the lights are less bright. That is very useful. (And because of the new side grills, you can also see some green light inside when powered on.)

The 100 back is very different—the power cord plug is on the right side, the speaker outputs are now on the left, and (as mentioned above) there is no power switch anymore. The analog out to speakers is now via solid metal (gold colored) banana adaptors included; no more cheap plastic. The adaptors can accommodate 3 connection types: banana, by snapping your banana plugs into the end, spades, by attaching to the solid metal screws near the end, and even bare wire by using the hole in the middle. Nice and convenient.

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How much better in sound quality?

The soundstage revealed by the Sprout100 is significantly larger/deeper than the original Sprout. Very impressive overall, the improvement is very noticeable; the sort of sound stage I would only expect from much more expensive amplifiers. The Sprout100 can make speakers seem to disappear; the sound appearing to come from the back and center up high, and with transparency and dead quiet when there should be. The natural timbre of instruments is displayed, and the type of venue (such as a church) can be discerned.

For speakers I used Alta Audio IO ($3500/pair), a small, remarkable 2-driver model with superb bass reproduction for its size (special thanks to Michael Levi, Founder and CEO of Alta Audio, for lending me a pair for this review). When I reviewed the original Sprout, I had used a pair of Alta Audio Solo, an exceptional, full-range single-driver model; but I decided to raise the ante given the 100 Watts per channel; the IO has an impedance of 4 Ohms, and a requirement of 50—150 Watts per channel. This turned out to be a first-rate pairing. (I also have heard the IOs with the original Sprout, and know that combination very well; a wonderful pairing, already.)

Here are some exemplary CD rip examples using digital: Ben Allison (Jazz bassist), Peace Pipe (2002). Allison has quite a touch for seamlessly fusing jazz with exotic non-Western influences (including Mamadou Diabate on the West African stringed instrument, the kora), this is my favorite album of his, check out Track 8, Disposable Genius’, and Track 5, Goin’ Back, Allison’s rendition of a piece written by Neil Young. American Beauty (2000) (sound track to the movie, Thomas Newman’s score); our Publisher introduced this album to me upon a visit to his home recently; man can that shake your listening room and your system with layers of complexity and a dynamic range challenge; various instruments include piano, tabla, saz, bass flute and even an Appalachian Dulcimer. Mick Jagger’s The Long Black Veil from the 1995 album by The Chieftans of the same name; listen to more of the album, too, with its Celtic theme; singers ranging from Sting to Sinead O’Conner, Mark Knopfler and beyond.

These sound observations held true even for Bluetooth streaming using 16/44.1 (CD rips) digital files; using Bluetooth alone from a laptop the Sprout100 excels in a way that many will probably choose to use as its main purpose, with speakers or with headphones. As in the original, the Sprout100 is small and light enough to easily fit in your backpack; taking it on a trip is easy.

Perhaps what is missing from this extraordinary $599 unit’s amps is a dash more 3-D imaging one would get (and better get!) from much more expensive amps (my reference mono blocks retail for $12K per pair); by which I mean the impression that individual instruments are floating around at different pin-point locations in space. 

The most impressive sound quality came from directly using the USB connection which yielded a lush sound with more air and spaciousness, never fatiguing; the USB improvement over the original model is exceptional. In this case, I used a Mac mini as music server. I used Roon Labs (and TidalHiFi with it). This allowed me to play high-resolution PCM files, and DSD at double rate.

I list here two convincing high-resolution digital examples from the Norwegian 2L download site. Sprout100 really shined; what an admirable job it did at handling them. Both albums are outstanding and new (April 2018), recorded digitally at 24/352.8 PCM. The first is Polarity—an acoustic jazz project by Hoff Ensemble; I recommend track 4 Polarity, and track 8 Euphoria with its mix of piano and drums. As described by the musicians themselves, “The character of Euphoria is elated—the spontaneous improvisation between the piano and drums driving the melody to a no-holds-barred level of energy.” (You’re not kidding!). The second is UTOPIAS-Radical Interpretations of Iconic Works for Percussion recorded in Jar Church in Norway (percussionist Kjell Tore Innervik). Thunderous drums of various kinds, bells, and yes you can tell it is performed in a church. Careful placement of microphones was used. Part of its purpose is to make you feel immersed in the performance—as if right in its midst; it succeeds. Check out the fascinating photos of the performance/venue.

Remote control

This was a surprise. The original Sprout did not have one; that was to be part of its simplicity and charm. But I guess many users wanted one. I tend not to use remotes unless they are necessary; otherwise one’s living space gets cluttered with so many remotes that things get very confusing. (For my reference system I only have 1 remote that controls both my preamplifier and DAC, and an iPad for using Roon Labs with the DAC.) The Sprout100 remote is nice and simple, it only controls volume, power on/off, and mute. Made of brushed aluminum, it is sturdy, solid, small, and weighs in at 2.5 ounces. It works well with the new infinity volume knob, pressing the +/− volume buttons causes the indicator light to blink for each step.

By chance, I found out that the remote is magnetic. It stuck to a metal protective case of my iPad, so then to be sure, I stuck it on my metal refrigerator door—sure enough! I like that feature, and I like this remote. McGowan confirmed to me that the magnetic feature was on purpose. I now keep it on the fridge door after listening sessions so I always know where it is—and so that my young kids can’t get their hands on it.

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Using Vinyl

When I reviewed the original Sprout 3 years ago, I did not even have a turntable in my system, and thus was not able to give a serious vinyl workout to the Sprout. Instead, I had brought the unit over to friends who had turntables just to get a basic idea of how things sounded. Things sounded OK. I also pointed out at the time that the Sprout will probably motivate me to begin building up a fine vinyl system after a 30 year lapse—it did. I now have a very satisfying (to me) vinyl set up: A VPI Prime Turntable, Pass Labs XP-17 Phono Stage, Grado Labs Statement v2 Cartridge, and used through a PS Audio BHK Signature Preamplifier and a pair of Merrill Audio Veritas mono block amps. Testing the Sprout100’s phono stage was a breeze and very satisfying—surprisingly so.

Setting things up merely required snapping the RCA cables out of my phono stage and into those of the Sprout100, and quickly connecting the grounding wire; it took 5 minutes at most. I powered the unit back on, turned the mode dial to ‘Vinyl’, and placed the classic Steely Dan album Aja on. Out came that same nice soundstage I had witnessed with the digital, and so did details, punchy bass and clarity.

I was concerned that my cartridge might not work well with the Sprout100 because the Grado is a moving iron, not a moving magnet. But the fixed 47K Ohms, 100pF was just fine, and the fact that the Sprout100 has a built in preamplifier allowed the volume to be adjusted just fine too–no gain issues. Remarkably, buzz distortion (e.g., when a record is not playing but the volume is up) was almost non-existent. In short: very satisfying for what it does. (Of course one can’t expect it to compete with my reference set up–and it did not; but it certainly did well; better than I would have thought.)

I then played the new album by Chris Barron (lead singer of the Spin Doctors), Strangers and One-Armed Jugglers, my favorite song, The World Accordian to Garp, with its funky use of
tuba, singing style a dash reminiscent of Simon and Garfunkel, and lyrics such as, ‘Like Elvis I’ve left the building, Boozy Susie on my arm……’.   Sounded great.

I then proceeded to one of my very favorite and outstanding LPs: Breaking Silence by Janis Ian. The Sprout100 made it sound musical and enjoyable; the snare drum sounded like a snare drum should with that snap and vibration. And of course Ian’s intimate voice came thru as it should. I was sold. Any more testing needed? Sure: Again one of my very favorite LPs, Janos Starker, Bach Suites for Unaccompanied Cello, Mercury (Box set of 3 LPs). I put on the famous Suite No. 1 in G. Did it render the natural timbre of his cello? Yes. Did it expose nuances such as Starker’s breathing while playing? Yes.

Headphone Amp

The headphone amp in the Sprout100 is noticeably more powerful than the original, requiring less volume, and the sound has more body, depth, and clarity than before. I used it (typically late at night) with three different models of Master & Dynamic headphones: MH40, MW60, and MW50. (The latter two can be used wirelessly, but I used all hardwired into the Sprout’s 1/4” output.)

Driving more powerful speakers

Michael Levy (of Alta Audio) stopped by for a listen the other day, and after a nice session, when he noticed my reference Alta Audio FRM-2 Celesta’s down on the floor out of service, we both knew what to do for fun: swap out the IO for the Celesta to see how the Sprout100 can handle these very serious speakers that cost $15K per pair, with a frequency response down to 29 Hz. We jumped right to it and played Bela Fleck’s classic cut Flight of the Cosmic Hippo. The Sprout100 drove them well, displaying more depth, more bass, more presence and shaking my couch. Of course they did not yield the sound quality that the Celesta shows off with when paired with my 700 W per channel reference mono blocks, and peripheral reference equipment—but confirming that a $599 Sprout100 can drive these speakers was a revelation.

Summary

At the mere price of $599, the new and improved Sprout100 Integrated Amplifier excels at all it tries to do; I am hard pressed to find anything wrong with it. A must for those wishing to have a full simple system with fine sound and low cost, it will pair well with just about anything you attach it to, and it only weighs 2.9 pounds. An absolute bargain by any measurement. Very highly recommended.

Further information: PS Audio