MSRP: $2195-$3279 USD



  • Excellent imaging
  • Good resolution
  • Great for Planars
  • Useful Lucid Mode
  • Responsive to Tube rolling
  • Very Fast sounding amplifier


  • Dual Knobs for volume control is useful and well implemented but can be a hassle
  • Those looking for a warm and full bodied ‘tubey’ sound out of the box should look elsewhere or be ready to tube roll


The Decware Taboo MKIV may be an amplifier with little coverage because of the brands business model. It may be tough to get a review sample of one but I personally believe that when people mention well sought after brands like Eddie Current or DNA, that Decware should be considered in the same breathe. My experience with this amplifier has given me this impression based on my experience with similarly priced amps like the Zana Deux (albeit limited), Trafomatic Head 2, and other amps reviewed here.

The unit that I reviewed was supplied by ZMF Headphones who is currently selling the amplifier on the website here: . In order to have the pretty Padauk wood base in the pictures you must order it from his site. Otherwise the other wood configurations are to be found on the Decware website here:  


Weight 17 lbs. ea.
Dimensions 8.5″ H x 7.25″ W x 14..75″ D
Chassis Steel/Wood
Finish Black Powder Coat Typewriter Finish
Base Solid hardwood / user interchangeable
Circuit type Single ended Class  A Pentode
Input voltage 2.1 volts for full output
Noise / Hum < 1 millivolt
Response 10 Hz ~ 80 kHz
Rectification 5Y3GT / 5U4 / 5AR4 tube rectification
Output tubes SV83 or EL84 / 6BQ5
Signal tube 6922 / 6N1P
Transformers Proprietary US Made UFO Transformers
Biasing Self-Biasing circuit – never needs adjustment
Resistors All resistors are precision WW/MF by DALE, VISHAY
Signal Cap Audiophile grade Cryo Treated Beeswax Paper Foil
Filter Caps Premium grade 500V electrolytic
AC cord Fused IEC connector provided with removable power cord
Consumption 75 watts at full power
Input jacks RCA type 24K Gold / Teflon
Output jacks Gold 5-way binding posts accept 8 gauge wire
Warranty Lifetime to original owner / 90 days on tubes
Figures double into loudspeakers.
4 ohms 500 mw
8 ohms 1000 mw
16 ohms 1200 mw
24 ohms 1500 mw
32 ohms 1600 mw
50 ohms 1700 mw
75 ohms 1700 mw
100 ohms 1700 mw
150 ohms 1700 mw
250 ohms 1700 mw
300 ohms 1700 mw
600 ohms 1700 mw



Finish and looks:

The version that I have for review is from the ZMF website in Padauk wood as mentioned in the intro. The caps near the transformer are engraved with the Decware logo and writing as a stamp of officiality which I think is a nice touch. The Padauk wood definitely looks a deep and solid orange in person so fear not of being really disappointed when seeing it in person.  


This unit has the balanced inputs which is an additional 650 dollars. I personally have a tough time swallowing that pill for balanced. This is especially since my brief A/Bing between single ended and balanced inputs yielded insignificant results. However someone whose DAC sounds much better balanced, the upgrade may be worth it. This unit has the ‘Standard 24K Gold/Teflon’ RCA inputs.

Tubes used were the stock Valve art Rectifier tube, Brimar Rectifier tube (300B variant), two Russian NOS 6P15P-EV output tubes, and an RCA 6922 input tube. As much as I understand the tuning and selection the Valve art Rectifier for that goal since it offers a brighter and more lively sound to the Taboo, I much preferred the Brimar’s natural timbre and more balanced and polished tone. The liquidity of the RCA was evident as well.

So for this review I used balanced inputs from my Pavane into the Taboo with the Brimar tubes and RCA input tube.


Part of the perks and quirks of the Taboo MKIV unit is that it has dual volume control knobs. I would love for the next iteration to also have a master volume control of possible because it can be a bit annoying to have to dial in the volume and get it both channels correct. If anything some engraved marks or lines would enable you to do it more accurately. In the rare instance that someone is putting up with a wacky channel imbalance from a headphone, or more practically speaking has worse hearing in one ear than the other, the dual volume control can be really useful. The easy way for me to get around the annoyance was to control the volume in Audirvana and leave the knobs alone. 

Now this Taboo only comes with a 4 pin balanced output jack. There is no way around that. You have to get your headphones balanced. I have had to use other headphone amplifiers that were not fully balanced before that had a 4 pin XLR headphone jack; with those amps I was able to use my 4pin to 1/4 inch adapter but it won’t work here. It is to my shallow understanding that the amplifier takes the input signal and internally converts it to balanced. That meant for testing I was unable to use the Utopia because it was not fully balanced.


I have had a bit of experience with crossfeed adjustments on headphone amplifiers and this by far sounds the most natural. It is not without it’s unpleasantries and has a close competitor with the crossfeed implementation of the Phonitor X. The thing that sets it apart though is that it doesn’t concave the imaging too much like a lot of other implementations do. The center image loses a bit of its substantiality but not too much. Depending on how far you go, you will get much better imaging and holography but if you crank it all the way up you will hear a reverb effect. I often tried to enjoy the amplifier with Lucid mode off and having a bypass switch made that an easy task but I would be lying if I said I didn’t enjoy it more with some of that Lucid magic in the mix. Lucid Mode also seemed to open the amplifier up a bit more in dynamic range and clarity, yet while it was off it had a bit more composure and directness. 




  • CLARITY 95%

The overall signature of the Taboo from my point of reference is punchy, fast, and neutral; more so than your average tube amplifier. It does have a colored sound to it but not in the way that most people think of when they usually hear that word in association with tube amps. The coloration is not centered around the midbass and lower midrange. Those seeking a warm amplifier can tube roll but that doesn’t seem like it is the goal that Steve from Decware had in mind, especially with the stock tubes being used. 


The bass of the Taboo is fast and punchy. If I could draw a parallel for comparison, it would be the Utopia in that it is punchy and fast but not particularly densely solid at its fundamental core. Listening to a bassist has them missing a bit of command and presence but sounding textured and resolved. Kick drums need just a bit more hardness and body at times but they usually come through with ample energy and speed. The Taboo MKIV to my ears sounds just a bit more sub bass focused than midbass focused. It is less wet than my Mogwai for sure and sounds a bit more accurate. The transients start and finish quicker than pretty much any fully tubed amplifier I have heard. Sub-bass on EDM definitely sounds good to me and is solid and extended. I get a good stocky, and firm sub bass rumble on bass drops but midbass performance is not as convincing to me. It also sounds more dry than your average tube amplifier as well giving it a more precise and less flattering sound. My personal taste can appreciate the punchy and responsive delivery of the Taboo bass as well as its detail but would prefer a bit more slam. A short comparison to the Eddie Current Zana Deux at a meet had the Taboo better with planar bass and the ZD sounding harder and firmer on dynamics. 


Decware’s Taboo MKIV delivers the goods in the midrange the most compared to it’s lower and upper band. The Voices on the Taboo are extremely clear with excellent ‘hear-through’ factor and resolve. The Upper midrange sounds a little high-lighted to my ears especially compared to my usual points of reference but with the right headphone it works wonderfully. On a headphone like the Atticus, you’d be hard pressed to find a better pairing based on tonality. Also, even though my T50 woody has some upper midrange glow and hash, the Taboo didn’t overdo it there and instead had a paradoxical ability to tame some of it’s nasties.  The lower and middle midrange positionally sound just a tad distant but never really to the point of sounding hollow. Upping the Lucid mode can mess with the timbre making them a little thinner with more reverb but equally more holography.

Up until the Taboo MKIV, the Mogwai (with upgraded caps) has consistently been a bit more resolving than the amplifiers that I have reviewed here save the HE-9. Well not anymore. While it may have more body and girth than the Taboo, the midrange of the MK4 is consistently better at separating voices from background vocals and revealing reverb trails. The Taboo does not give the most lush midrange I have heard but the clarity and lack of veil makes it stand firm in it’s price tier. This is not to be taken as a lack of fullness at all. In fact it will sound more full and fleshed out than just about any solid state amp I can recall.  Male voices though have good texture and cut through the recording very well. The results of its tonality make snares lack just a bit of body from the lower midrange but good clarity and punchy from the upper midrange; this makes the timbre sound snappy but not visceral.

With both tubes, the stock and Brimar Rectifier tubes, or the RCA input tube didn’t really change the inherent tonality of the Taboo but the Brimar tube was preferred over the stock tube. The Valve art Rectifier tube (stock) was a bit hashy, tipped up, brittle, and lacked some body. The Brimar tube gave it some warmth in the midrange and sounded more refined and less gritty than the stock Valve art tube. 


The treble is very much like the bass in that it is resolving, extended, and decently fast but lacks just a bit of weight. After comparing it to the ZD and hearing cymbals I find that the Taboo could again use a bit more solidity or body. There is enough sheen and glimmer to the cymbals and the sibilance is never overdone but there is a bit of softness compared to my usual references. Otherwise it is again clear and present with good speed. There is no mistaking the Taboo for a solid state amplifier as there still is a bit more of that realism to the tones than your average colder sounding solid state amplifier delivers. There is also good nuance in the treble and decent details in the upper band that allow reassurance that it’s hefty price tag is merited. 


The Taboo is a high end amplifier, make no mistakes about it. It has good finesse, flow, and control.

Macro-dynamics are pretty good. The speed the amplifier gives makes it sound quick to the task with abrupt, focused, and on point transient response. Dynamic range seems okay to me as well if not just a hair less intense than my references consider ideal yet more than the Auris HA2SE. 

Micro-Dynamics or small nuances are a cut above most if not all of the previous amps I have reviewed. Very good in this area. 

Timbre is an area I would like to see improve. When I hear snares or kick drums and anything that drives the rhythm of the music I consistently have a slight want for a bit more meat and body. Just a bit more sustain would sound more realistic to my ears but quite often does something that sounds this fast also sound less meaty. 

The Taboo has quick attacks with the every instrument popping out distinctly from the other on its own plane. The decay sounds natural to me, even more so than most solid states, but it is still precise without extra decay. 

It has good separation and excellent imaging. As previously mentioned the Lucid more adds to the MK4’s ability to image but can cause reverb. Another effect of Lucid mode is that it opens up a bit and can have a more natural bloom. Finding the right setting for you can have you finagling with the knob more than necessary but it is a useful feature and possibly the best crossfeed implementation I have heard. The soundstage is very holographic and decently deep making my Mogwai sound a bit flat and lacking depth. However, the Taboo doesn’t have the best soundstage width; in that regards it is about average or slightly below. 



I like the Taboo MKIV a lot. My first impressions of it had me just a little slack jawed. After more listening I still like the amplifier but I wonder if having all of the options installed is worth it. It brings the amps price up to over $3k USD at which point I believe after 2.3k you are paying for more functionality than sound improvement. I actually enjoyed it with just about every headphone I tried from planar to dynamic except the HD800 on select songs. Were someone looking for a higher end fully tube amplifier for planars than the Taboo and Mogwai should be at the top of their lists however the Taboo is more technically impressive. The Mogwai (upgraded caps) gives a bit more slam and has a timbre more to my liking but otherwise the Taboo is more impressive and in some ways has raised the bar. 

Decware, based on my most recent experience with amplifiers, has produced a noteworthy amplifier in my opinion that has a lot going for it at a justified price. Pretty good amplifier for sure. 


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