Ferbose
Headphoneus Supremus
- Joined
- Jun 27, 2004
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There has been much discussion lately about Sonic Impact class-T digital amplifier. Since it is relatively inexpensive, I decided to give it a shot and evaluated it in my speaker system. After 100+ hours of breaking-in and no apparent changes in its sonic character for the last few days, I decided it is time to describe my experience with this little sonic wonder.
Review equipment (MSRP; Purchase Price):
Sonic Impact T-amp ($40, $30 from Target)
Transport/SACD player: Sony DVP-NS900V (Initially $1000; Open Box $480)
DAC/Preamp/headphone amp: Benchmark DAC1 ($975; $975)
Soundstage review’s choice product: http://www.soundstage.com/revequip/benchmark_dac1.htm
Stereophile product of the year 2004 (Editor’s Choice category): http://stereophile.com/features/1204poty/index7.html
Integrated hybrid (tube/MOSFET op-amp) amplifier: Jolida JD 301A ($350; $310) + Yugo 12AX7
A lower-power (30W) version of better known Jolida models 1701A and 1501A. 301 is said to sound very similar to both except for perhaps slightly weaker bass. Audition Audition had a very positive review of 1501 that can be freely accessed, but the link is lost. I uploaded the review here (IE required) http://www.its.caltech.edu/~tai/JD%201501.mht
Speakers: Athena S2/P2 combination ($1175; $1000)
Soundstage product of the year in “exceptional value” category in 2000.
A full review is here: http://www.soundstage.com/revequip/athena_s2p2.htm
Power: Belkin Surgemaster II ($40). Vector car battery booster ($50, fully charged 13.4V, 19 Ah). Brandless wall-wart ($15, 12V, 1.2 A).
Cables: (everything cheap and commonplace): Radio Shack coaxial digital cable, RCA to mini plug cable, 12V 5A DC cable, 16 AWG speaker wire. Hosa 1/4” plug to RCA cable. Rapco stereo RCA cable.
Headphone (as sonic reference): AKG K501
Features and Uses
Quick Summary: Initially I was worried if built-in volume knob or less-than-perfect external power supply may negatively affect its sound. But I found these worries to be unnecessary. To my surprise, it never clipped during one week of testing in my room (13’ x 9’), partly because T-amp’s high resolution allows me to listen clearly at lower volumes.
Appearance: cheap plastic box weighing less than one pound
Front: Volume knob that also functions as power switch
I tried various things to determine if the volume knob can negatively affect sound quality. The answer is basically no. Comparing full-on versus 1/2 and 1/4 settings, using sources with variable outputs, sometimes full-on sounds better and sometimes worse. The difference is so subtle it could just be my imagination. After an exchange of posts with other head-fiers, I feel that the volume knob can have positive or negative effects depending on upstream and downstream equipment. I don’t think volume control quality needs to be a concern here, at least when it’s new and turning smoothly.
Back:
(1) Speaker connector: cheap spring clips.
The clips barely accept my 16 AWG wires. Forget about using banana plugs or spades, because they will never fit.
(2) Audio input: 1 x 3.5 mm stereo plug
If you are wondering why it is called a digital amplifier and only has analog input, then you should definitely read this article for clarification.
http://www.audioholics.com/techtips/...mplifiers.html
Class T amplifier is just a variation of switching amplifier (Class D analog amplifier design) that has been around for a long time. The name “digital amplifier” is just a marketing phrase.
(3) Power adapter:
Accepts 5.5 mm OD/2.1 mm ID type DC connector between 12-14V, commonly found in wall warts. I am using booster battery for my car to operate T-amp, which happens to be here. It is essentially a 12V lead rechargeable battery. Since the amp is expected to run 6-12 h on 8xAA batteries, my booster should last 20 times longer. T-amp can require 2A at maximum output, while my battery can output 400A peak current and my DC cable has 5A fuse. Although lead battery can provide highest-quality DC, a 1.2A, 12V cheap wall wart does not seem to affect sound quality either. Maybe the highs are bit edgy with the wall wart, but it seems so subtle that it can be my imagination. If I don’t have the car booster, I would buy a 13.8 V, 3A Radio Shack power supply myself.
Bottom: Battery compartment for 8xAA, not tested.
Output power: Based on Tripath’s datasheet, it outputs 6 W per channel into 8 ohms, and 10W into 4 ohms. My speaker has 8 ohm impedance and is measured at 88.5 dB (anechoic/2.83V/1m) by Soundstage.com. My room is 13 by 9 feet and playing loud orchestral music is not an issue for T-amp. 6W is a lot less than what people are used to but enough for many situations. I also find myself listening at lower volumes on T-amp than my Jolida amp, possibly because T-amp has greater resolution and let me hear clearly at lower volumes. I haven’t experienced clipping on T-amp and can’t comment on what that would sound like.
T-amp driving headphones
Based on posts shared by fellow head-fiers, T-amp’s output level is too high for ordinary headphones and too low to be used with Antique Sound Lab UHC. Some kind of DIY attenuator/adapter is required to hook up ordinary phones to T-amp. Several head-fiers also reported that T-amp match quite well with K1000, and volume control does not seem to affect sound quality in such uses.
Mini-conclusion:
T-amp performs well as it is. It can be used as a power-amplifier or as an integrated amplifier with a single source. Its price and sonic performance (see below) makes it suitable for simple gaming systems all the way up to audiophile speaker systems.
Sonic Impressions: Sonic Impact T-amp vs Jolida JD301
Quick summary:
Within the confines of SI’s 6 meager watts, which are quite sufficient in my setup, it is a better amplifier than Jolida. Yes, that is a $30 amp outperforming a well-reputed $350 integrated amp. SI wins out mainly because of its resolution and transparency. SI also has tighter bass, faster attack, added presence and better imaging. In comparison, Jolida’s tube section lends itself to fatter bass, smoother highs and more diffused sound. SI’s highs seem brighter, and in some instances can be sibilant, thin or edgy. However, it is never harsh and nor does it present fake detailed feelings resulting from excessive treble. Its high frequency range contains a lot of musical information, but in my particular setup and room, it does not always render very well. Jolida’s tube nature makes more pleasant renditions than SI in certain situations, but on the musicality scale they score equally well. At the end of the day, SI brings me closer to the original performance and therefore it will replace the Jolida.
(1) About the Jolida
When researching on this unit, multiple online user comments indicate that Jolida JD 301 sounds better than entry level NAD integrated amplifiers (C320, C340 etc.). Unfortunately, I never had a NAD or Rotel in my home to compare to. Jolida has developed a very good reputation for great-bang-for-buck tube audio electronics in North America. JD 301 is a hybrid amplifier with two 12AX7 tubes and two LM1875 power IC. LM1875 also appears in the highly regarded 47 Labs Gaincard amplifier. I have Jolida sotck 12AX7, Yugo 12AX7 tubes, and TNT-selected Chinese 12AX7. Yugo is used in this review because it is what I generally prefer. Compared to Chinese tube, it is less resolving but more musical, but the differences are slight. Stock tubes are clearly inferior. Bill Baker of Response Audio actually thinks quite highly of JD301 and once marketed a modified version of it called RAM 301.
(2) Setup:
Evaluations are done on CDs with the Sony as Transport and the Benchmark as DAC.
T-amp (powered by voltage booster) is connected to Benchmark’s headphone out. Volume knob is fixed at 1/2 on T-amp and actual volume control is performed by Benchmark. I feel this configuration gives most smoothness for the combo, which is preferred.
Jolida is connected to Benchmark through RCA output in fixed mode (maximum voltage level). Volume control is performed on Jolida. I feel this configuration gives best resolution for the combo, which is preferred.
(3) Music:
I listened to many CDs on each amp, and here is a list of CDs that best illustrate their differences.
a. Claudio Arrau, The Final Sessions, Vol 2 (Philips 434626-2)
Beautifully resonant piano recording, great for detecting high frequency anomalies. On Jolida, the percussive nature of piano seems a bit dampened. SI better articulates piano sound. SI sounds detailed and clean without being bright or thin. Jolida shows a tiny bit of ringing at one particular note. SI gets the nod on piano sound.
b. What about this Mr. Paganini? Violins of Amati, Guadagnini, Guarneri, Hovarth, Stradivari, Vuillaume (Tacet 36)
Amazingly realistic (through Benchmark and K501) recording of seven great violins compared side-by-side. Since I played the violin as a child and often hear it in concerts, I use this disc to evaluate the highs. Admittedly, my Athena speakers do not reproduce believable violin notes, especially the higher ones. I think Athena is a bit dark and grainy compared to K501. Jolida’s tubes add roundedness to violin’s high notes, which is enjoyable. SI actually differentiates the sonic characters of each violin better, but all of them sound a bit edgy. This is not to say SI generally sound brittle in high frequency, because high piano notes sound better on SI. Jolida gets the nod on smooth violin sound.
c. The Ultimate Demonstration Disc: Chesky’s guide to critical listening (Chesky UD95)
It is an invaluable disc for audiophiles, because each musical track is preceded by an explanatory narrative track on what to listen for. It tells me what to expect if my system is near-perfect, so I don’t have to guess. Using tracks 5 and 23, I find no discrepancy in three-dimensionality of these two amps, either in soundstage depth, width or height. On track 23, a choral recording in a big cathedral, both recordings show astounding soundstage height. On SI, the beautiful reverberations make me think they are reflected from stone, which is probably the actual case. On Jolida, the sound is softened and diffused so it sounds like a tall wooden hall—less real but more fun. IMO this is a great example of how these two amps voice in different but equally valid ways. Track 7 shows that SI produces cymbals more clearly than Jolida. SI gets the nod on extreme high frequency.
d. Rebecca Pidgeon: Retrospective (Chesky hybrid SACD, SACD242, CD layer used for evaluation)
Track 1 (the famous Spanish Harlem) is the remastered version of previous CD’s track 3. SI has tighter bass that is more realistic compared to Jolida’s fatter bass. Maraca is heard very clearly on both, showing that neither lacks details. However, SI separates maraca more clearly from other instruments and defines it better in space. Track 3 is very beautiful and simple female vocal. SI renders it with pleasant sibilance. Jolida makes it darker and fuller. Not knowing what Rebecca’s real voice is like, I can only say they are equally enjoyable. SI gets the nod on bass, imaging and resolution.
e. The New Tango: Astor Piazzolla and Gary Burton (Atlantic 781823-2)
This is the most surprising find of the day. I always thought it is a mediocre early digital recording (1987), because it sounds kind of muffled with Jolida. It sounds cleaner through K501 headphones, but still not impressive. But this recording really wakes up with SI. Through SI, it shows a lot of presence, which is probably a combination of clean sound, good stereo mixing to create imaging and airiness, and some forwardness. SI gets the nod on presence.
(4) Further sonic comments
T-amp is simply great for its resolution, not just great for its price, but just great per se. K501 and Benchmark’s headphone output is not the last word in resolution, but it is certainly very good. T-amp and Athena speakers, connected to the same headphone output, give almost as much resolution. I assume Athena S2 is not as resolving as K501, and therefore I guess T-amp basically causes no loss in resolution. The only negative thing I observed during T-amp testing is that solo violin passages sound edgy. At the same time, T-amp outperformed Jolida in other high frequency areas such as piano, vibraphone and cymbal. This leads me to suspect that my speakers are actually responsible for the violin glitches I hear. Jolida’s tubes certainly cover up this better, but with T-amp I am also able to modify my room acoustics and tweak with speaker grilles to make much of the glitch disappear. T-amp is brighter than Jolida (tubed), but I suspect all solid state stuff is. I don’t know if T-amp is bright on an absolute scale, because I don’t have megabuck speakers and amplifiers to serve as references. In the mids and lows, T-amp excels at everything I threw at it. Although T-amp looks lightweight, it produces a weighty sound--cello has a surprising degree of realism on SI/Athena combo. In the highs, it still outperforms Jolida, but my system admittedly isn’t hi-end enough to determine its actual shortcomings, which may or may not exist.
Mini-conclusion:
In terms of tonality and voicing, SI and Jolida are philosophically different. T-amp offers what I would expect in a good solid state amp: transparency, speed, attack, rhythm, presence, and some brilliance. Jolida uses good, old 12AX7 to soften the sound, which is quite preferable in some situations. But SI simply has more resolution and detail, so it comes out as the winner. Jolida is falling behind in terms of fidelity, but the musicality of both amps is excellent.
Final Conclusions:
Even when T-amp is used with cheap cables and wall-wart, its performance is still a level above my beloved Jolida. In my experience, cleaner power supply can improve the sound a tiny bit. Its built-in volume can make it sound a bit better or worse based on upstream or maybe downstream equipment. T-amp’s great resolution allows listening at slightly lower levels, and therefore its 6W is very sufficient for my use. T-amp really works as advertised, and its ease of use gets a “10” on my scorecard. During my one week evaluation, T-amp did most things right and if I had find fault it would be a few minor glitches in the highs. To be fair, my speakers and older amplifier, though much more expensive than T-amp, are not hi-end enough to help me identify whether the glitches I hear actually come from the T-amp. I consider T-amp a piece of genuinely hi-end gear, just like my Benchmark DAC1 and AKG K501. For $30 it truly is a no-brainer. I would strongly recommend it for simple computer speaker setup all the way up to hi-end speaker systems.
Pros: bargain-basement price, sonic strengths of very good solid state amps, ease of use, relative insensitivity to cheaper connections and power supply, small footprint.
Cons: None for its asking price.
Compared to hi-end amps: lower power and cheap connectors.
Sonically, I can’t identify apparent faults. If I have to guess, it would be some sibilance in highs and the volume control can change its sonic properties a tiny bit (for better or worse seems setup-dependent).
More thoughts on the T-amp:
After one week with the T-amp, I have to ask myself, how can such a cheap amp sound this good? Here is my educated guess. Class-T amplifier IC is new class of chip design aimed at providing good sound. Given the advances of semiconductor technology, it is not surprising that ICs can also improve in terms of sound quality. Bel Canto’s new digital amplifiers also use class-T chips and I have heard nothing but praise for them in audio magazines. Usually, designing hi-end electronics requires careful tuning of the circuitry to improve the sound. Still, without such hi-end purposes in mind, sometimes a piece of mass-market electronics can be designed right on the mark to sound really good. I think this is what happened with T-amp. Sonic Impact products are designed for ipod users. But most ipod users have no need for a 6W amp because they don’t buy passive speakers. I am not sure if T-amp is selling that well, because few on-line stores carry it. I am worried if T-amp will go out of production soon. I am actually considering buying a second T-amp and preserve it for later use. I would recommend audiophiles even remotely interested in this amp go out and grab one right now.
Review equipment (MSRP; Purchase Price):
Sonic Impact T-amp ($40, $30 from Target)
Transport/SACD player: Sony DVP-NS900V (Initially $1000; Open Box $480)
DAC/Preamp/headphone amp: Benchmark DAC1 ($975; $975)
Soundstage review’s choice product: http://www.soundstage.com/revequip/benchmark_dac1.htm
Stereophile product of the year 2004 (Editor’s Choice category): http://stereophile.com/features/1204poty/index7.html
Integrated hybrid (tube/MOSFET op-amp) amplifier: Jolida JD 301A ($350; $310) + Yugo 12AX7
A lower-power (30W) version of better known Jolida models 1701A and 1501A. 301 is said to sound very similar to both except for perhaps slightly weaker bass. Audition Audition had a very positive review of 1501 that can be freely accessed, but the link is lost. I uploaded the review here (IE required) http://www.its.caltech.edu/~tai/JD%201501.mht
Speakers: Athena S2/P2 combination ($1175; $1000)
Soundstage product of the year in “exceptional value” category in 2000.
A full review is here: http://www.soundstage.com/revequip/athena_s2p2.htm
Power: Belkin Surgemaster II ($40). Vector car battery booster ($50, fully charged 13.4V, 19 Ah). Brandless wall-wart ($15, 12V, 1.2 A).
Cables: (everything cheap and commonplace): Radio Shack coaxial digital cable, RCA to mini plug cable, 12V 5A DC cable, 16 AWG speaker wire. Hosa 1/4” plug to RCA cable. Rapco stereo RCA cable.
Headphone (as sonic reference): AKG K501
Features and Uses
Quick Summary: Initially I was worried if built-in volume knob or less-than-perfect external power supply may negatively affect its sound. But I found these worries to be unnecessary. To my surprise, it never clipped during one week of testing in my room (13’ x 9’), partly because T-amp’s high resolution allows me to listen clearly at lower volumes.
Appearance: cheap plastic box weighing less than one pound
Front: Volume knob that also functions as power switch
I tried various things to determine if the volume knob can negatively affect sound quality. The answer is basically no. Comparing full-on versus 1/2 and 1/4 settings, using sources with variable outputs, sometimes full-on sounds better and sometimes worse. The difference is so subtle it could just be my imagination. After an exchange of posts with other head-fiers, I feel that the volume knob can have positive or negative effects depending on upstream and downstream equipment. I don’t think volume control quality needs to be a concern here, at least when it’s new and turning smoothly.
Back:
(1) Speaker connector: cheap spring clips.
The clips barely accept my 16 AWG wires. Forget about using banana plugs or spades, because they will never fit.
(2) Audio input: 1 x 3.5 mm stereo plug
If you are wondering why it is called a digital amplifier and only has analog input, then you should definitely read this article for clarification.
http://www.audioholics.com/techtips/...mplifiers.html
Class T amplifier is just a variation of switching amplifier (Class D analog amplifier design) that has been around for a long time. The name “digital amplifier” is just a marketing phrase.
(3) Power adapter:
Accepts 5.5 mm OD/2.1 mm ID type DC connector between 12-14V, commonly found in wall warts. I am using booster battery for my car to operate T-amp, which happens to be here. It is essentially a 12V lead rechargeable battery. Since the amp is expected to run 6-12 h on 8xAA batteries, my booster should last 20 times longer. T-amp can require 2A at maximum output, while my battery can output 400A peak current and my DC cable has 5A fuse. Although lead battery can provide highest-quality DC, a 1.2A, 12V cheap wall wart does not seem to affect sound quality either. Maybe the highs are bit edgy with the wall wart, but it seems so subtle that it can be my imagination. If I don’t have the car booster, I would buy a 13.8 V, 3A Radio Shack power supply myself.
Bottom: Battery compartment for 8xAA, not tested.
Output power: Based on Tripath’s datasheet, it outputs 6 W per channel into 8 ohms, and 10W into 4 ohms. My speaker has 8 ohm impedance and is measured at 88.5 dB (anechoic/2.83V/1m) by Soundstage.com. My room is 13 by 9 feet and playing loud orchestral music is not an issue for T-amp. 6W is a lot less than what people are used to but enough for many situations. I also find myself listening at lower volumes on T-amp than my Jolida amp, possibly because T-amp has greater resolution and let me hear clearly at lower volumes. I haven’t experienced clipping on T-amp and can’t comment on what that would sound like.
T-amp driving headphones
Based on posts shared by fellow head-fiers, T-amp’s output level is too high for ordinary headphones and too low to be used with Antique Sound Lab UHC. Some kind of DIY attenuator/adapter is required to hook up ordinary phones to T-amp. Several head-fiers also reported that T-amp match quite well with K1000, and volume control does not seem to affect sound quality in such uses.
Mini-conclusion:
T-amp performs well as it is. It can be used as a power-amplifier or as an integrated amplifier with a single source. Its price and sonic performance (see below) makes it suitable for simple gaming systems all the way up to audiophile speaker systems.
Sonic Impressions: Sonic Impact T-amp vs Jolida JD301
Quick summary:
Within the confines of SI’s 6 meager watts, which are quite sufficient in my setup, it is a better amplifier than Jolida. Yes, that is a $30 amp outperforming a well-reputed $350 integrated amp. SI wins out mainly because of its resolution and transparency. SI also has tighter bass, faster attack, added presence and better imaging. In comparison, Jolida’s tube section lends itself to fatter bass, smoother highs and more diffused sound. SI’s highs seem brighter, and in some instances can be sibilant, thin or edgy. However, it is never harsh and nor does it present fake detailed feelings resulting from excessive treble. Its high frequency range contains a lot of musical information, but in my particular setup and room, it does not always render very well. Jolida’s tube nature makes more pleasant renditions than SI in certain situations, but on the musicality scale they score equally well. At the end of the day, SI brings me closer to the original performance and therefore it will replace the Jolida.
(1) About the Jolida
When researching on this unit, multiple online user comments indicate that Jolida JD 301 sounds better than entry level NAD integrated amplifiers (C320, C340 etc.). Unfortunately, I never had a NAD or Rotel in my home to compare to. Jolida has developed a very good reputation for great-bang-for-buck tube audio electronics in North America. JD 301 is a hybrid amplifier with two 12AX7 tubes and two LM1875 power IC. LM1875 also appears in the highly regarded 47 Labs Gaincard amplifier. I have Jolida sotck 12AX7, Yugo 12AX7 tubes, and TNT-selected Chinese 12AX7. Yugo is used in this review because it is what I generally prefer. Compared to Chinese tube, it is less resolving but more musical, but the differences are slight. Stock tubes are clearly inferior. Bill Baker of Response Audio actually thinks quite highly of JD301 and once marketed a modified version of it called RAM 301.
(2) Setup:
Evaluations are done on CDs with the Sony as Transport and the Benchmark as DAC.
T-amp (powered by voltage booster) is connected to Benchmark’s headphone out. Volume knob is fixed at 1/2 on T-amp and actual volume control is performed by Benchmark. I feel this configuration gives most smoothness for the combo, which is preferred.
Jolida is connected to Benchmark through RCA output in fixed mode (maximum voltage level). Volume control is performed on Jolida. I feel this configuration gives best resolution for the combo, which is preferred.
(3) Music:
I listened to many CDs on each amp, and here is a list of CDs that best illustrate their differences.
a. Claudio Arrau, The Final Sessions, Vol 2 (Philips 434626-2)
Beautifully resonant piano recording, great for detecting high frequency anomalies. On Jolida, the percussive nature of piano seems a bit dampened. SI better articulates piano sound. SI sounds detailed and clean without being bright or thin. Jolida shows a tiny bit of ringing at one particular note. SI gets the nod on piano sound.
b. What about this Mr. Paganini? Violins of Amati, Guadagnini, Guarneri, Hovarth, Stradivari, Vuillaume (Tacet 36)
Amazingly realistic (through Benchmark and K501) recording of seven great violins compared side-by-side. Since I played the violin as a child and often hear it in concerts, I use this disc to evaluate the highs. Admittedly, my Athena speakers do not reproduce believable violin notes, especially the higher ones. I think Athena is a bit dark and grainy compared to K501. Jolida’s tubes add roundedness to violin’s high notes, which is enjoyable. SI actually differentiates the sonic characters of each violin better, but all of them sound a bit edgy. This is not to say SI generally sound brittle in high frequency, because high piano notes sound better on SI. Jolida gets the nod on smooth violin sound.
c. The Ultimate Demonstration Disc: Chesky’s guide to critical listening (Chesky UD95)
It is an invaluable disc for audiophiles, because each musical track is preceded by an explanatory narrative track on what to listen for. It tells me what to expect if my system is near-perfect, so I don’t have to guess. Using tracks 5 and 23, I find no discrepancy in three-dimensionality of these two amps, either in soundstage depth, width or height. On track 23, a choral recording in a big cathedral, both recordings show astounding soundstage height. On SI, the beautiful reverberations make me think they are reflected from stone, which is probably the actual case. On Jolida, the sound is softened and diffused so it sounds like a tall wooden hall—less real but more fun. IMO this is a great example of how these two amps voice in different but equally valid ways. Track 7 shows that SI produces cymbals more clearly than Jolida. SI gets the nod on extreme high frequency.
d. Rebecca Pidgeon: Retrospective (Chesky hybrid SACD, SACD242, CD layer used for evaluation)
Track 1 (the famous Spanish Harlem) is the remastered version of previous CD’s track 3. SI has tighter bass that is more realistic compared to Jolida’s fatter bass. Maraca is heard very clearly on both, showing that neither lacks details. However, SI separates maraca more clearly from other instruments and defines it better in space. Track 3 is very beautiful and simple female vocal. SI renders it with pleasant sibilance. Jolida makes it darker and fuller. Not knowing what Rebecca’s real voice is like, I can only say they are equally enjoyable. SI gets the nod on bass, imaging and resolution.
e. The New Tango: Astor Piazzolla and Gary Burton (Atlantic 781823-2)
This is the most surprising find of the day. I always thought it is a mediocre early digital recording (1987), because it sounds kind of muffled with Jolida. It sounds cleaner through K501 headphones, but still not impressive. But this recording really wakes up with SI. Through SI, it shows a lot of presence, which is probably a combination of clean sound, good stereo mixing to create imaging and airiness, and some forwardness. SI gets the nod on presence.
(4) Further sonic comments
T-amp is simply great for its resolution, not just great for its price, but just great per se. K501 and Benchmark’s headphone output is not the last word in resolution, but it is certainly very good. T-amp and Athena speakers, connected to the same headphone output, give almost as much resolution. I assume Athena S2 is not as resolving as K501, and therefore I guess T-amp basically causes no loss in resolution. The only negative thing I observed during T-amp testing is that solo violin passages sound edgy. At the same time, T-amp outperformed Jolida in other high frequency areas such as piano, vibraphone and cymbal. This leads me to suspect that my speakers are actually responsible for the violin glitches I hear. Jolida’s tubes certainly cover up this better, but with T-amp I am also able to modify my room acoustics and tweak with speaker grilles to make much of the glitch disappear. T-amp is brighter than Jolida (tubed), but I suspect all solid state stuff is. I don’t know if T-amp is bright on an absolute scale, because I don’t have megabuck speakers and amplifiers to serve as references. In the mids and lows, T-amp excels at everything I threw at it. Although T-amp looks lightweight, it produces a weighty sound--cello has a surprising degree of realism on SI/Athena combo. In the highs, it still outperforms Jolida, but my system admittedly isn’t hi-end enough to determine its actual shortcomings, which may or may not exist.
Mini-conclusion:
In terms of tonality and voicing, SI and Jolida are philosophically different. T-amp offers what I would expect in a good solid state amp: transparency, speed, attack, rhythm, presence, and some brilliance. Jolida uses good, old 12AX7 to soften the sound, which is quite preferable in some situations. But SI simply has more resolution and detail, so it comes out as the winner. Jolida is falling behind in terms of fidelity, but the musicality of both amps is excellent.
Final Conclusions:
Even when T-amp is used with cheap cables and wall-wart, its performance is still a level above my beloved Jolida. In my experience, cleaner power supply can improve the sound a tiny bit. Its built-in volume can make it sound a bit better or worse based on upstream or maybe downstream equipment. T-amp’s great resolution allows listening at slightly lower levels, and therefore its 6W is very sufficient for my use. T-amp really works as advertised, and its ease of use gets a “10” on my scorecard. During my one week evaluation, T-amp did most things right and if I had find fault it would be a few minor glitches in the highs. To be fair, my speakers and older amplifier, though much more expensive than T-amp, are not hi-end enough to help me identify whether the glitches I hear actually come from the T-amp. I consider T-amp a piece of genuinely hi-end gear, just like my Benchmark DAC1 and AKG K501. For $30 it truly is a no-brainer. I would strongly recommend it for simple computer speaker setup all the way up to hi-end speaker systems.
Pros: bargain-basement price, sonic strengths of very good solid state amps, ease of use, relative insensitivity to cheaper connections and power supply, small footprint.
Cons: None for its asking price.
Compared to hi-end amps: lower power and cheap connectors.
Sonically, I can’t identify apparent faults. If I have to guess, it would be some sibilance in highs and the volume control can change its sonic properties a tiny bit (for better or worse seems setup-dependent).
More thoughts on the T-amp:
After one week with the T-amp, I have to ask myself, how can such a cheap amp sound this good? Here is my educated guess. Class-T amplifier IC is new class of chip design aimed at providing good sound. Given the advances of semiconductor technology, it is not surprising that ICs can also improve in terms of sound quality. Bel Canto’s new digital amplifiers also use class-T chips and I have heard nothing but praise for them in audio magazines. Usually, designing hi-end electronics requires careful tuning of the circuitry to improve the sound. Still, without such hi-end purposes in mind, sometimes a piece of mass-market electronics can be designed right on the mark to sound really good. I think this is what happened with T-amp. Sonic Impact products are designed for ipod users. But most ipod users have no need for a 6W amp because they don’t buy passive speakers. I am not sure if T-amp is selling that well, because few on-line stores carry it. I am worried if T-amp will go out of production soon. I am actually considering buying a second T-amp and preserve it for later use. I would recommend audiophiles even remotely interested in this amp go out and grab one right now.
