Qinpu A3 Integrated Amplifier

***This is a follow up to my initial review. Still amazed at the sound especially now that I've had a chance to break it in for hundreds of hours. The new model works perfectly and is not flawed like the first unit that was returned and replaced with another a3.I did add some Audioquest Golden Gate Interconnects this time around and that made just enough improvement to the muddy base (tightened up the bass just enough ) on some recordings to add another half star to the review rating. If it had more power and more outputs I'd give it a 5 star rating. I'm sure a more expensive interconnect would tighten up the bass even more on the bad recordings but at least now the muddiness is gone and won't overwhelm the rest of the recording.***ORIGINAL REVIEW BELOWHooked this up to a pair of Mirage OM 10 speakers with AudioQuest Type 4 cable. CD Player is a Cambridge Audio D300 SE.Replaced the stock tubes out of the box with JAN GE NOS 5670 model. Later after a burn in period of about 20 hours of operation, I replaced these with the stock tubes. I observed the following. Stock tubes have a nice sound but with less enhanced bass and a slightly brighter mid range and highs. Definitely a bit of improvement over the sound I had previously when using my Cambridge Audio A 300 integrated amp. Overall a slightly smoother sound with the A3.I noticed a clear improvement though when I used the GE 5670 tubes. Initially the bass was pretty boomy on some songs but that cleared up after about ten hours of playing music. The audio had a very mellow sound and the bass was much improved over the stock tubes. Mid range and highs were smoother and individual instruments were easier to pick out in most songs. The clarity of the music also improved and previously hidden details with certain instruments started to emerge with these tubes in place.I used a variety of music during the the 20 hour break in period. Classical was the least improved music over the Cambridge Audio amp. It became slightly smoother but not overwhelmingly so. Noticeable improvement was heard to older rock, R&B and Soul recordings especially those from the 60's and early 70's. It was a night and day difference. Bass became much tighter, instruments were more detailed and exhibited certain sounds that previously were muddled or not heard at all. It was as if the recordings had been remastered or re recorded at a later time in the studio. I also noticed a great improvement to most Jazz recordings as well. Used Smooth and Contemporary Jazz recordings from the 70's through the late 90's. Almost as much improvement as with the older rock recordings but not quite as dramatic.I think I would have seen even more improvement over the older amp if I had a different set of speakers. I purposely bought the Mirage OM 10's in 1999 because they were well known for having a mellow sound. They have a 90 db sensitivity which is ample to drive this amp. My previous speakers were Klipsch Heresy's and I am certain if I still had those, the sonic improvement would have been dramatic to say the least. They had a harsh sound that resulted in listening fatigue after a couple of hours of use. But since tube type amps are known for creating a more silky, smooth sound and I did not pair this amp with more harsh sounding speakers I did not see quite as much improvement as might be expected with more traditional box speakers. I also have a pair of Castle Conway 3 speakers in storage and those being a more traditional box speaker might very well show more improvement to the audio once I can pair them with the A3. Still, the improvement is noticeable with the OM10's and worth the $199.00 price tag.The negative. One channel started to cut out on some songs that had heavier bass when I moved the audio playback level to around a quarter length turn on the A3. I tried swapping cables and also switched the cables to the other channel but to no avail. Even trying the 1/8" mini plug did not help. Audio at a low playing level was fine but at a moderate level the problem started. Never tried a high volume level. This was a defective unit that will be returned but I plan to replace it with another A3 and will hope it is free from defects.Overall I am very pleased with the sound and it seems evident you could spend ten times as much money for a solid state amp that still won't offer the same kind of sound that you get from a tube type amp. Even one that is integrated with a solid state amp like the A3. If you want a mellow, silky sound to your music then this amp will not disappoint you. This component offered the biggest improvement the sound of my system since I replaced the Heresy speakers with the OM 10's. Arguably the improvement created by the A3 even exceeds that level of quality realized with the change in speakers.After I receive the new amp and have a chance to break it in even longer I will follow up this review with another.

UPDATE NOV 7 2012:I've been listening daily to this little wonder for over a year now and still can't get enough of it. This model appears to be discontinued but I'm sure the A-6000 sounds just as good (and has a lot more power output): Qinpu - A-6000 MKII - Integrated /Headphone Amplifier Happy listening, whatever gear you're enjoying! - Andrew--I've been auditioning this little Chinese hybrid tube/solid-state amp for two weeks now and here are my comments:* Really natural and enjoyable tube amp sonics that compare well to old all-tube integrated amps that I've tried out (several vintage MacIntoshes, Marantzes, and a rheumatic Admiral).* No, I haven't heard the newish Miniwatt, Roth, Fatman, Qinpu A6000 or Q2 (I'm cheap & also wanted headphone preamp functionality and this model fit the bill).* A very hip "retro dork" desktop alternative to powered PC speakers or iPod speaker dock--everyone in my office stops to stare at the eerie glowing vacuum tubes* Utterly bizarre yet charming product design: One hella-solid "ovaloid" brushed metal brick (the frame IS the heatsink), reminiscent of those 1950's space station posters from Maoist China's bygone space program ("Comrade, please experience most natural pleasure-creating heavenly musicality for such reasonable cost!")* Volume and source selector dials: excellent "touch" (dampening), and acceptable (though not rock-solid) input/output jacks* Speaker out thumbscrews - unimpressive build here (plastic, wish they were metal) but they've proved sturdy and snug so far* Note: There's NO speaker on/off switch (signal is always going to the preamp-out jack and the speakers), so if you want to switch between headphone-only listening and speaker listening, you'll need a speaker switchbox or similar workaround* IS 8.6 WATTS ENOUGH? Tested: 1) RA LABS BLACK GOLD MINI-REFERENCE (90db/2.83V/1m/6ohm) and 2) MISSION CYRUS 782s (91.5db/1m/4ohm), 3) INFINITY RS1 bookshelf satellites (89db/1m/8ohm). With the volume knob at 50%, there was plenty of power to create realistic acoustic small-ensemble jazz/chamber live performance volume in a 14x17' room, even though the speaker manufacturers recommended 20, 25, and 15 watt minimums, respectively.* With ye olde Dual TURNTABLE, good vinyl sounds quite alive and engaging (though not as razor sharp as the NAD amp mentioned below). There's no phono-in stage on the Qinpu, so you'll need your own.* As a HEADPHONE PREAMP, sound is transparent, virtually noise-free, and very dimensional with Grado SR60, SR80, and Sennheiser HD600 headphones. Power is just adequate and could be "punchier," especially with the higher-impedence Sennheisers.*[UPDATE]] As a PREAMP STAGE looped in to an integrated amp (NAD 315BEE), sounds great, with one caveat: low but audible noise floor (around -65-70 db), but that may be coming from the crappy grounding in my house, YMMV. Hook-up details: I connected the A3 "headphone" port to the NAD "Pre-Amp In" RCA ports. This makes the A3 serve as the pre-amp and the NAD as a simple amplifier. So the volume is entirely controlled by the A3 (as with all pre-amp/amp stacks).* Channel separation, S/N ratio, and distortion specs for this amp don't tell the whole story--soundstage imaging and "believability" of acoustic jazz, chamber music, and vocals is uncanny. Specs below.** To really hear this thing's engaging dynamics and soundstage depth, I highly recommend running your CDs and FLACs through a free ambiophonic plug-in or player--eliminates listening-room speaker crosstalk and comb filtering to restore the original stereo imaging. Here, it's a JAW-DROPPING improvement (search for "ambiophonics" or Hotto Engineering)* Also, give this unit a good 4-8 hours of "break-in" time to give the tubes a chance to get groovin' (or to allow the "audiophile placebo effect" to kick in, whichever comes first) ;)* Attention push-pull purists: This is a "hybrid" (tube preamp and solid-state amp)...but sounds pure valve to meVERDICT: For the price of a fancy iPod speaker doc or a Tivoli One, this is the obvious choice if you already have some fairly easy-to-drive speakers lying around the garage. Yep, it's a "bargain basement" item, but I can't stop listening to this thing! I've logged 4-6 hours a day since I got it. And this is also a most excellent vendor covered by Amazon's reasonable exchange/returns policy.My disclosure blurb: I'm not an audio engineer and everything above is subjective. Also, I'm not associated in any way with Qinpu or Kraft Street Audio (I'm a commercial photographer and copywriter in the music and book publishing industry).Happy tubing! - Andrew--Equipment used: Macbook native DAC (24bit 96khz) and Streamer II external DAC fed into the Qinpu's RCA audio-in jacks * 160gb iPod Gen 3 * loudspeakers and headphones mentioned above * Dual 1219 turntable with Grado ZFE+ cartridge and NAD PP2 phono preampSome reference recordings used:Paquito D'Rivera | "The Jazz Chamber Trio" | Chesky RecordsOttmar Liebert | "One Guitar" | 24bit 96khz DVD-A | Spiral Subwave RecordingsBuena Vista Social Club | 24bit 96khz DVD-A | NonesuchCalamus | "Splendor of An-Andalus | MA RecordingsDoc Watson & David Grisman | "Doc & Dawg" | Acoustic DiscElla Fitzgerald & Louis Armstrong | "Ella & Louis" | 24bit 96hz SACD | VerveEugene Istomin & Seattle Symphony ORchestra | Mozart Piano Concertos 21 & 24 |Reference RecordingsV.M. Bhatt | "Saradamani" | 180gm vinyl LP | Water Lily AcousticsJohn Renbourn | "Sir John Alot..." | vinyl LP | Nonesuch*Qinpu A-3 specifications from their website:Output power: 2 x 8.5W (8-ohm RMS)Frequency response: 20Hz-40kHz (±1dB)THD: less than 1.5% (1kHz)S/N ratio: greater than 71dBCrosstalk attenuation: greater than 45dB (1kHz)Input sensitivity: less than 420mVOverload level: greater than 10VInput impedance: 15k-ohmNet weight: 5.1lbDimensions: 10.25" x 5.5" x 0.433"

I bought this little amp based on the price and the great reviews that it had received. I used this amp to drive my desktop speakers, a pair Paradigm atoms and as a headphone amplifier for my ATH-50's. Right out of the box I was very impressed, it sounded so great hook up to Paradigm's and had power to spare, the stereo separation was incredible. The headphone experience was very good as well, but the output level was a little too low for ATH-50's and left wishing for a little more volume. All was good for a about a month and a half and then something in the amp fried. The pre-amp sound output was massively distorted and also the speaker output. I contacted the seller for help and received prompt reply stating that being that I bought the amp through Amazon there was nothing they could do or would do to help. After contacting Amazon the Amazon customer service folks graciously let me return the amp after the 30 day return window and even paid for the shipping. I am very happy to have used Amazon for this purchase otherwise I would be stuck with a $200 tube amp shaped boat anchor. I just wish the manufacture would have stood by their product and replaced it as I will not take a chance on them again even though it was such a great performer and a great price. So it's back to searching for the prefect little tube amp for my desktop.My breakdown would look like this.Speaker sound quality 4.5 starsHeadphone amp quality 3 starsLooks 4.5 starsreliability 1 starAmazon experience 5 starsManufacture experience 0.5 stars