Equipment Review No. 1   February 2002

Smart Theatre Systems 2X150VT
Hybrid Power Amplifier

Smart Devices, Inc.
5945 Peachtree Corners East
Norcross, GA 30071
(800) 45-SMART voice
(770) 449-6728 fax

Basic Description

2 channel power amplifier with a 6922 dual triode input tube; 150 Wpc 20-20kHz at 8 ohms < .9% THD/ 240 Wpc at 4 ohms <.04% THD 20-20kHz/ 500 W at 8 ohms <.04% THD 20-20kHz monaural; 5.8" H, 15.8" W, 10.1" D; 23 lbs.; detachable IEC power cord; input level trims; ground lift; also available in non-tube version with better specifications; 3 year parts and labor warranty including tube replacement and/or tune-up after 3 years with return shipping paid; rack-mount kit available.



System 1: Monster HTS1000, Sunfire Tube Preamplifier, Sunfire Stereo Amplifier Series 1 ($2375)-for comparison, B&W CDM7 NT speakers, Linn Genki CD player, Tara Labs cabling. System 2: Meridian 568 Preamplifier, Krell KST-100-for comparison, Philips CDC-935 CD transport, Revel F30 speakers, PS Audio P300, MIT, Audioquest, and Discovery cabling.



When I first opened the box and pulled the Smart Devices amplifier out, I was surprised. I thought that perhaps I was sent the wrong unit-it looked like an old Hafler DH-200 amplifier I used to own. Well, not exactly. This amp has a very nice stainless steel top with a tube hiding behind a small transparent window. The company appears to be very proud of the look of the amplifier, and have dubbed it the "Stainless Steel Stradivarius."

Inside the small packet that comes with the amplifier is a "Certification of Performance" that shows distortion (THD?) vs. frequency response, but does not indicate power output, impedance, whether both channels are driven, etc. I assumed this was at rated output into an 8-ohm load. According to the graph, the amp's channels were very closely matched (within .005%), and the distortion remained below .125% except after 10kHz where it went up to about .0125%.

Along with the manual came a little brochure on the amplifier explaining design philosophy and some of the other features offered by the amplifier. The manual states that the amplifiers are burned-in for a period of 5 days under load conditions to insure the unit can "stabilize so that maximum sonic quality is available immediately." I also let the unit stay on for a period of two days before I began any listening tests and left it on during the period of time I spent with the unit.

On the back of the unit are a few adjustment options. One switch allows bridging the unit to mono, and another allows lifting the chassis ground to reduce/prevent hum. I did not have a second amp to try the bridging, and didn't have hum/noise when the ground lift switch was in either position. There are input levels in the back adjacent to the RCA inputs, but I left these all the way up during all my listening tests. Purists would say that the performance might be improved if they had been left off completely. Smart suggests that they might help match the amp better with certain preamplifiers, but I myself did not have any difficulty with the two preamplifiers used in this review.

In addition, there are three fuses that could be user-serviced/replaced. Two of these are fast-blow types designed to protect the amplifier should the speaker wires touch. They could also be replaced with smaller value fuses to protect the speakers from damage due to high levels (of which this amplifier is surely capable!) The line cord is detachable, and although it comes with a fairly heavy-duty cord, gives the opportunity for those who like to tweak such things, to do so.

The 5-way binding posts are very close to each other, as unfortunately found on many amps today. They are labeled "1" and "2" although the input jacks are clearly color-coded to indicate left and right. With System 1, I used banana plugs for quick switching so there was no difficulty with plugging and unplugging. In system 2, I used thicker MIT speaker cable with spade lugs, and tightened the connections with an Audioquest wrench. The positive speaker output connection was a bit loose and did not always tighten properly. After switching speaker wires several times, some of the other leads started spinning not tightening as well. I was able to make the connections snug by pushing and twisting at the same time. I had the amplifier sticking out the front of my rack so I could easily switch speaker wires for comparison. This meant less trouble caused by the location of the jacks. Otherwise, I was able to get it to function well enough during this testing. If I had decided to keep this amplifier, I would probably opt to replace these connections with some terminals that are more rugged.  For the most part, the Smart amp has a very solid feel to it, but the power switch is soft and plastic.


Listening--System 1

After a long warm-up I was anxious to hear how this amplifier performed. I put on track 4, "Any Love," from Norman Brown's After The Storm. Right away I was very impressed with the sound, and can understand why many people have been very taken with the sound of this amplifier. There was a nice sense of delicacy to the high frequencies. All the instruments came across as smooth and warm. There was a pleasing sense of space and three-dimensionality. There was an authority to the sound that was especially evident in the bass, and control of the speaker was never in question. What was most impressive was how non-fatiguing the Smart amp was. I was busy tapping my toes, almost forgetting I was supposed to be in review mode. The B&W speakers and the rest of the system seemed to be in harmony with the Smart amp. When I switched over to the Sunfire amp, there was a definite change in sonics, especially in the high end. The sound was steelier, more metallic; it had more sizzle. The bass was more inflated and punchier, and a tad deeper. Mids and highs had a slightly different quality to them through the Sunfire amp. With this track, the Smart amp was easier to sit back and listen to.

Next up was track 7, "Cousin Dupree," from Steely Dan's Two Against Nature. My notes say smooth in big letters. All the instruments were presented in realistic sizes that would be heard in a live concert. This recording can have too much sizzle on a lot of different systems I've heard, but not here. Part of this was, no doubt, due to the Sunfire tube preamplifier, but also can be attributed to the Smart amp. At times the bass was almost overpowering. With the Sunfire amp in the system, there was more spittiness and sibilance on vocals, and percussion had more scratchiness to it. The sound was not edgy, however. The Sunfire amp drew more attention to the individual instruments in the soundstage rather the presentation as a whole. The Smart amplifier tended to blend a little, and give a more homogenous presentation that didn't make individual elements stand out as much.

I wanted to hear what the Smart amp could do with a little piano, so I put on track 3, "Kei's Song" from David Benoit's Freedom At Midnight. The Smart presented a large sound with good tonal balance. Percussive effects were well integrated into the soundfield. Strings were clearly set behind and rendered further back into the mix. The reverb of the piano was clear and easily heard. At louder levels, and when the recording got louder, there was a slight hardness on certain notes, but it was more related to the recording than the Smart amp. The Sunfire offered a glassy sound with more sparkle on top. There was not as much front-to-back layering as there seemed to be with the Smart amp.

With Zigeunerweisen, Op. 20  by Pablo De Sarasate with Anne-Sophie Mutter and James Levine conducting the Vienna Philharmonic Orchestra, I felt as if the dynamic range was being slightly restricted with the Smart amp. Sound was rolled off in space. There was some congestion on the violin as well. The Sunfire had more edge and was woodier sounding.

The last listening with System 1 was "Kalerka" by Rebecca Pidgeon from The Raven. Both amps did a great job on this recording. The vocal image seemed a tad bigger on the Sunfire with more inflection in the voice. Other than that, I had nothing to complain about and a lot about which to compliment the Smart amplifier.


Listening--System 2

To start off the listening with System 2, I put on "I Wish" by Skee-Lo, track 5 on MTV Party To Go Volume 8. Strangely, the Smart amp seemed to make the sound slower than with the Krell. I could only guess that the transient response was not as good on the Smart although its specifications would seem to indicate extremely good damping factor, extended bandwidth, and more than enough current capability to drive the Revel F30s. There was a very slight haze over the sound that gave it a pleasant ease. Percussive sounds were not as biting and bright as with the Krell amp. With the Krell, images were more focused in the soundstage, but with more edge, and slight harshness. Some of this was program related, but the Smart amp definitely made it easier on the ear.

I switched gears and put on a little Renee Rosnes, track 3, "Abstraction Blue," from As We Are Now. With the Smart there was a slight blending of sounds and/or softening. The midrange was mellow in comparison to the Krell. With the Krell, the reverb on the recording was more noticeable. Different piano notes were more distinct, attacks and transient sounds were more obvious. Dynamics seemed better, but sound had hardness to it overall.

An interesting recording with all sorts of strange and enjoyable effects is track 1, "Everything In Its Right Place," from Radiohead's Kid A album.

With the Smart, the soundstage was bigger, but had less focus than with the Krell. Images could be heard outside the edge of the speakers with both amplifiers. Voice was more present in the mix with the Smart, but had a slight puffiness to it. The Krell offered more focus, and images were more locked in. There was a greater sense of air between the foreground and the background sounds. There was a slight edge on metallic sounds not present with the Smart, but not enough to be an irritant. The Krell revealed more of the recording, but along with that came an analytical sound that for some may not be preferred to the euphonic sound imparted by the Smart amp.

On "The Day the World Went Away," track 2 from The Fragile  by Nine Inch Nails, the guitar with the Smart amp was not as gritty as I expected. It seems as if the sound is being held back, making it palatable, but not giving me the onslaught of guitar sound. There was some softening happening with some of the edginess on the recording being removed.

On track 9, the Adagio-Allegro spiritoso of Haydn's Symphony in G "Oxford" with Karl Bohm conducting the Vienna Philharmonic Orchestra, the Smart delivered sound that was sweet, easy, mellow, with less listener fatigue than with the Krell. I found the sound very appealing with a slight emphasis on mids that gave strings a full-bodied quality. The Krell was not as sweet, but images that were deeper in the soundstage were portrayed with greater resolution. Sound was more expansive front to back with greater sense of reverb.

Lastly, I put on track 4, "I Get Along Without You Very Well," by Billie Holiday on Lady In Satin - surely not my sentiments regarding this amplifier! With the Smart it was easy to forget about the equipment and just relax to the seductive sounds. The sound from the Krell was not as smooth, and voice had a more remote character especially on high notes. Like the last track auditioned, this one really showed off the strengths of the Smart amp.


If you long for the lack of irritation and hardness found in many typical solid-state hi-fi systems of today, then the Smart 2X150VT may be the answer. On the surface it may look like an amp from the past, but it is surely a different beast altogether. It delivered a pleasant, non-fatiguing sound without resorting to the rolled-off, dynamic restricted, power-limited sound present with many heat-generating all-tube designs, or, the sterile, analytical sound of many solid-state amplifiers. The Smart amp is small and compact, but attractive and powerful. If you have a system that is lacking in resolution due to a poor amplifier, or needs some warmth to get you through the harsh, cold sound of certain CD's, then the Smart Theatre Systems 2X150VT power amplifier should be on your list of amplifiers to audition.

- - Brian Bloom

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