INFI Audio Hybrid Class AB Tube Amplifier 6N3 Power Amp with Bluetooth Home Audio HiFi Stereo Receiver Integrated Amp AUX Bluetooth USB Charger Optical Coaxial Sub-Out

Let me start off by saying wow! You get a lot of value with this amp. The highs are sparkling and accurate. The mids are clear and full. I have not hooked up a sub yet so I can't comment on the low end yet. I can't wait to slap some vintage Mullard tubes in and give it a rip. For less than $200, this is a bargain especially with a toroidal transformer. I haven't pushed it past half volume yet as it gets plenty loud, but I will stretch its legs when my 3yr old is out of the house.Pros:Fit and finish are greatHighs and mids are clear and warmVU meters work wellPower ratings are accurate and this will crush lesser digital 100w amps12AX7 Tubes are available everywhere, and I will experiment with different modelsStereo separation between channels is superb and has no detectable bleed overCons:There is an LED underneath the tubes giving the illusion they are being pushed harder, they still do get hot, but they're just taking care of the preamp16bit-44k sampling rate max on bluetooth, it would be good to get aptX with 24/96kNo headphone output on frontVolume knob should be on front and the source select should be on top with the bass and treble, but that's me just being picky

I purchased one of these as a simple tube amp to add to a room in the house and give it a shot. I plugged everything in and warmed it up but within the first 15 minutes it started with a low static that grew to a loud tea kettle like whistle that got very very loud and then it would just go quite. I would have to turn it off for about 10 seconds then turn it back on to get sound again. Again and again after just a few minutes to about 15 minutes it does the same thing. Very annoying. I asked for tech service and was sent another unit. The same exact thing happened with the second. I asked the seller if they could just send the part that would fix it because when it was on for the short amount of time it did sound good and I could fix it. The seller was going to send a tested working unit out or one of the newer models and I even was willing to pay the extra and appreciated the willingness to get me a working unit. I sent the unit back and then was met with a message from the seller asking why I did that and then silence from that point on until I had to message them asking if we were done so that I would at least know what was going on. They said yes and that is that. I really wanted to like this. It looks great, sounded good but very very unhappy with the two in a row that I received. You get what you pay for I guess but even for the low price of this tube amp it is not worth it if they don't even work fully.

The media could not be loaded. TL;DRFor DIY audio nerds: As a ‘sandbox’, FIVE STARS, buy it! Worth the money for the $exy chassis and parts alone. Lots of mod possibilities,For the average consumer: 3.5 STARS, Good value and decent sound for the money but be aware of Q,C, issues.For ‘audiophiles’: (Rating stars like money are of no object) Something of a curiosity, like the Optimus CD-3400, Sounds better than you would expect for what it is, but certainly no ‘giant-killer’.PROS:Great lookingSurprisingly pleasing soundGreat valueGood component qualityUseful placement of Volume control (for my setup)CONS:Poor final assembly/build quality/workmanship (my purchased unit)Subwoofer pre-fade (volume control does not affect subwoofer output)Mechanical and electrical noisePRELIMINARY REVIEW:I normally would not get near a product like this but needed something to stand in for my ST70 (vintage tube amp) while I restored it. I saw the INFI-AD05 on youtube, was attracted by the styling, and bought one thinking I could gut in and put decent electronics inside if it turns out to be junk.Unboxing I was immediately impressed with the elegant understated design of the IF-AD05. It looks right at home with my living room decor. The exterior fit and finish were good except a misaligned Bass knob, which was easily removed and reinstalled correctly. The controls feel buttery smooth. It certainly has the look and feel of a more expensive product.I was a little apprehensive about plugging it in to some very expensive speakers, but curiosity got the best of me and I powered it up,,,and kept my finger on the power button,,,,,With the volume control at zero and nothing but speakers connected INFI-AD05 came to life and greeted me with hum and digital ‘chatter’ noise. This is certainly no ‘audiophile’ product, not even close. I thought “You get what you pay for, back in the box to Amazon it goes”. But curiosity got the best of me and I decided to give it a listen. Feeding the RCA inputs from a Schiit Modi 3 DAC I played my go to HiFi eval albums; Stravinsky - Rite of Spring(Dutiot/Montreal Symphony), and Peter Gabriel - Passion. I’ll bypass all the fluffy audiophile terminology and just say it sounded pretty good to my ears, not great, but certainly listenable.I thought “I can live with a little noise temporarily, I’ll use the INFI as a stand-in then see what I can do with it once ST70 is restored”Moving the AD05 I noticed something heavy wobbling around inside (now we’re back to “where’s that shipping box”). I know that unless they put a brick in it the only thing that heavy is the xfmr so I decided to open it up and see what’s loose. Sure enough the single bolt that secures the toroid was completely loose and the transformer was flopping around like a drunken sailor.Okay, easy fix. And with a little wire dressing the noise improved. Looks like I have my new (temporary) amp.I’ll briefly summarize the good, bad and ugly I’ve found after doing some reverse engineering and using the IF-AD05 for a month.Good:>Classic A/B power amp on through hole PCB (imho through hole sounds better than SMT)>Clean minimal signal path (ceramic coupling capacitors, some redundant, can be upgraded/bypassed)>Spkr protection relay>4558 Op-Amps (not bad or ugly)>Modular design, easily serviceable>160VDC B+ (higher would be better, but not bad)>Audio switched by relays>‘Cookie Cutter’ design, simple building blocks, almost don’t need a schematic>Consumer grade components/electronics, nothing esoteric, good for the priceBad:>Subwoofer output pre-fade, no easy cut&jump mod to change due to phase flips baxandall tone and sub LPF>Digital noise and AC hum in speaker outputs>Mechanical 60Hz noise from transformer>Linear pot used for volume control>Electrical safety ground not properly bonded to chassis, no star washers or lock nuts, connected to plate that sits on top of amp module (UL okay with this?)>Bias network transistor not in thermal contact with heatsink where it belongs, will cause amp to run hot, (but closer to Class-A!)>Preamp PCB uses identical connectors that could accidentally be swapped, better keyed color coded for serviceability.Ugly:No attempt at wire dressing, total rat’s nest, Is there a shortage of tie-wraps in China?Transformer bolt not secure, split washer not effective as mounting plate bends, better solution needed to secure toroid xfmr.R Ch installed 12AX7 popping, crackling, microphonic, should not have passed a properly implemented final test.(my purchased unit)A few more notes on the design:The tubes are implemented as cathode followers post fade and feed the power amp inputs. The cathode follower implementation is a little strange in 2 ways: 1- Triodes are paralled but one plate is disconnected (pin 1) 2- Both channels are connected to B+ via a shared 220K resistor (haven't bench tested yet but CROSSTALK?!?!). Subwoofer outputs are on a separate path and not routed through the tubes.Thermal management; Fan activation seems to be based on input levels and has nothing to do with the heatsink temperature or amp load.Bluetooth Module; Works okay for casual listening, nice to have as a convenience, BT has an exposed serial port.I don’t really have the time or feel a need to put the AD05 through a bench test and evaluation, I suspect it’s not going to do much better than the similar Monoprice product reviewed by Audio Science Review.Mods:To better suit my IF-AD05 to my needs and likings, I made a couple quick ‘wire sculpture’ mods so I now have:>No ceramic capacitors in the main signal path>Post-fade subwoofer outputs (subwoofer outputs controlled with main volume)>Bypassed tone controlsThere’s plenty of room to work on the preamp PCB, I can imagine lots of possibilities for Audio DIY’ers.

WOW... just WOW! This INFI hybrid tube amplifier is worth every penny and the build quality is very good. It has brought my old Jensen floor speakers to life! Music separation and projection is so realistic that it sounds like the musicians are in the room! I use it mainly for Bluetooth streaming and connection took only seconds!UPDATE SEPTEMBER 13TH 2021After months of daily use I am still enjoying amazing sound from this unit! I have connected my turntable through a hybrib pre amp into this Infi unit. Audiophile vinyl recordings is where this thing really shines! UNBELIEVABLE! I will be upgrading tubes soon just for fun! I will update everyone.UPDATE OCT 2022In Feb 2022 one of the original tubes went bad and I replaced both tubes with a gain matched pair of JJ 12AX7 tubes. After 15 or so hours of use the new tubes settled in nicely and the INFI amplifier is still putting amazing sound in my ears. The JJ tubes were a noticeable improvement over the stock tubes. Still loving every note! This thing is still putting great sound in my ears!!! July 10 2025!