[Review] Human Audio - Muto DAC(s) and Tabla converter

Human Audio Muto DAC(s) with Tabla USB converter

High Definition DAC and interface

Product name: Human Audio Tabla and Muto DAC's.
Manufacturer: Human Audio
Cost for Muto (DAC with JFet output stage):
North America (US/Canada): US $1199 from True Audiophile webshop
European Union: € 1015 (incl. VAT) direct sales from Human Audio

Cost for Muto-X (DAC with output transformer):
North America (US/Canada): US $1799 from True Audiophile webshop
European Union: € 1523 (incl. VAT) direct sales from Human Audio

Cost for Tabla (USB converter):
North America (US/Canada): US $995 from True Audiophile webshop
European Union: € 761 (inclusive of VAT) direct sales from Human Audio

Reviewer: Nick Whetstone - TNT UK
Reviewed: February, 2013

You may remember a quite unique CD player that I reviewed from Hungarian company Human Audio back in January 2011. One of the key features of the Libretto system was that it was battery-powered, something that Human Audio feel very strongly is a necessary feature of top-end hi-fi gear. So it is no surprise that their Muto high end DAC's (there are two versions) and the matching USB converter, The Tabla, are also battery powered, this time by a couple of internal LiFePO4 batteries.

The Libretto was a bold design statement in it's bamboo casing, and came with a price tag to match. The Muto is a much more restrained design in a black metal casing with an acrylic front plate that allows the indicator lights. There are lights to indicate battery condition and charging, input choice, LOC, and HDS. If you have been put off by too many bright LED's staring at you from your hi-fi rack, don't worry about the number of them on the Muto as they are very discreet. Another acrylic plate on the rear provides a mirrored finish to show off the gold-plated socketry that includes (much to my approval) a BNC input socket, as well as an RCA (phono) input socket. There are also phono output sockets, a socket for the 5 volt charger that is supplied, and two small switches, one to turn the unit on and off, and the other to switch between the two inputs. With dimensions of 100mm by 50 mm x 130mm the Muto is slightly larger than the usual Hammond style case but as it is designed to stand on it's edge, it has a very small footprint. Build quality feels substantial, and the overall appearance is quite classy.

The two versions of the Muto that I referred to are identical as regards the DAC stage but have different output stages, one using a Jfet buffer, and the other (the Muto-X) having a transformer output. The two look identical and I could only tell the difference between them by the weight, 651 grams (transformer) and 536 grams (Jfet) although the serial number also identifies the version.

Other differences between the two Muto's are:
MUTO:
- analog stage: fully discrete output using bipolar and J-FET transistors in "Class-A" operation
- it has lower (non-standard) output level which is 1.25Vrms
MSRP: 999 EUR including VAT

MUTO-X:
- analog stage: fully passive, transformer output with true balanced operation
- the operation time with one charge is a bit longer than normal Muto. (~ 13-15 hours
) - the charging isn't possible during switched-on. When the batteries reached the low (red) state after 13-15 hours continuous usage (assumed full charge) the BAT indicator led goes to red from green. That time it has about 40-80 minutes remaining operation time (in red state) before automated switching-off and also automated starting of charge.
- the forced re-charge is about 6 hours only
- it has standard 1.45Vrms output level which is also useable as real and true (!) balanced (xlr) signals as well since those (L & R RCA outputs) are totally independent from each other. So no common grounding at all.
(schematic of the conversion cable included)
Price inclusive of RCA to XLR adapters (to allow connection to a balanced amplifier)

[Rear view of Human Tabla]

Connecting the Jfet DAC to the (supplied) charger is straight forward. Once charged it will play for around 12 hours but if you need to go longer than that, you will see a red light on the front of the unit, and you can simply connect the charger as the power supply is completely isolated from the signal path. The Muto-X uses less power and will play for around 14 hours but cannot be used while it is charging (unlike the Muto). When you turn the Muto off, the batteries are then fully charged up again after 12-14 hours (but only 6-8 hours for the Muto-X).

The Tabla is a USB converter, ie it takes the signal from the computer via a USB connection, and supplies an SPDIF signal to a separate DAC. It looks almost identical to the Muto DAC's, and a Tabla/Muto combination will take up less space than half a hi-fi shelf. The Tabla is also powered from a LiFeP04 battery, which is charged by the 5 volt supply from the computer (via the USB cable that also carries the signal). There is a switch on the rear panel to turn it on and off so that it won't run down the battery while the computer isn't connected, or turned off. Connections are straightforward, USB cable between computer and a socket on the rear, and an SPDIF cable from the BNC socket on the rear to the DAC.

The battery charging is automatic so there is no need to remember to turn chargers on and off. When the battery is too low to play music, the charger comes on automatically and a filtered supply allows the user to continue listening while the batteries are charged up at the same time. The batteries will last at least 5 years before their performance starts to deteriorate due to memory effect. LiFeP04 batteries are renowned for their safety too, quite important if we are leaving them to be charged overnight, or while we are away from home.

[Rear view of Human Audio Muto]

The Tabla appears to use (going by the driver that has to be installed on the computer before it can be used) a version of the M2-Tech HiFace interface. I had attempted to review the original HiFace a year or so back but for some reason, connecting the unit to my PC locked it, requiring a reboot. I'm pleased to report this time that there were no such problems, and the driver was installed in a few minutes without any issues. The driver was downloaded from the Human Audio web site.

I first auditioned the Muto DAC with the Jfet buffer using the Tabla converter. The Tabla connects to a computer, a laptop in this case, and is then connected to the DAC via an SPDIF cable. The DAC is connected to an amplifier (or pre amplifier) via analogue interconnects. The laptop used had Windows 8 installed, and was running JPlay as the playback software.

John Kenny of JKDAC fame told me that we are still in the pioneering stages of using computer audio, and I agree. So it is with much hope for the future that I listened to the Tabla/Muto combination and realised how far we have come already. This combination is a world away from the early CD players, and the separate DAC's of the same era. The first thing I noted down was how much more analogue they sounded, and I think that is in a large part due to the battery power supplies.

The Tabla/Muto combination reminded me much of the DIY HiFi Cleo that I reviewed last year. The pair dig deep into the recording to bring out masses of detail that is presented in a very pleasant (analoguesqe?) manner. The bass is very well defined and bounces happily along providing the PRaT that makes music so enjoyable. The midrange is open and detailed, as is the top end without ever being harsh or difficult to listen too. The sound stage is large (wide and deep) and airy, and the imaging accurate. Like the Libretto, the Tabla/Muto combination is predominantly musical. Detail is so clear that I could easily discern lyrics that are hard to pick out on lesser equipment. I also noticed with late night listening that there just seemed to me so much 'more' at lower volume levels. Percussion was particularly well portrayed making drums sound quite real.

It's hard to find anything negative to say about the sound other than I still wonder if there isn't a tiny bit more firmness to the bass lines with a mains powered DAC. That said, I would be quite happy to live with the positives of the Tabla/Muto combination myself instead of that last bit of bottom end clout. However, my favourite combination of converter/DAC was the Tabla paired with the MHDT Stockholm DAC. With it's stronger, more 'forceful' presentation, the Stockholm was the ideal partner for the battery-powered Tabla, at least in my system, and produced some of the best sounds that I have heard anywhere. I sometimes wonder if there is a perfect system for all types of music, and I found trying different combinations of converter and DAC often produced a sound that favoured a particular genre. And the Tabla/Muto combination I would say just favoured acoustic music rather than hard rock (both Muto and Muto-X).

It's difficult to know what more we can ask from a source, but perhaps the answer lies in playing some higher resolution music through the Tabla/Muto. As with lower resolution, so much depends on the quality of the recording, but on a good one they really made me appreciate the advantage of 24bit/192 hz resolution. The improvement is most noticeable on 'busy' recordings such a full-scale orchestral music where the finer details are preserved better. That gives the listener a better insight into the music being played, and recreates the ambience of the location where the performance took place. I appreciated the higher resolution recordings more in this review, no doubt due to using JPlay that I hadn't had available for the Cleo review.

Swapping the Muto for the Muto-X with its transformer output stage gives a different sound that I can only describe as a bit more transparent, effortless, and a bit more 'airy'. At first I couldn't say which I preferred but over the weeks that I listened to the Muto's, I found myself wanting to put the 'X' version back in the system more often than the Jfet version. Then I changed amplifiers and found that I slightly preferred the JFet version. Overall though I preferred the 'X', and used that while testing some other stuff that I had for review at the same time.

[Phono to XLR adapters to allow balanced connection between Muto X and balanced amplifier]

The Muto-X also comes with XLR converter plugs (included in the purchase price) that convert it into a balanced source. That will be particularly appealing to users with a balanced amplifier or pre amplifier.

While I had the Tabla and Muto's for review, I also managed to get hold of the similarly specified JK products, the SPDIF Mk 3 (Tabla alternative) and the JKDAC32 that is a converter/DAC in a single box. Without going into too much detail (because I have written separate reviews of the JK products), I just preferred the Tabla to the SPDIF Mk3, but preferred the JKDAC32 to the Tabla/Muto combination. The JKDAC32 uses the same interface as the S/PDIF Mk3 but uses a different DAC chip(PCM1502). The truth is that there are so many variables in a USB DAC set-up that it makes it hard to do simple AB comparisons. While the JK products come with a significantly lower price tag, it must be noted that the price of the Tabla/Muto is reflected in the quality of their finish, and their extra features.

The Tabla and Muto DAC's are class acts, and ones that I really enjoyed listening too. In almost every session, I excitedly put on music to see what it would sound like through them. Even after a week or two I still felt that I was rediscovering music on my hard drive. Handling them probably gives a better impression of their build quality than pictures do, and makes the prices seem more competitive. It's true that compared to the JK products, they may look a little expensive but a Bentley looks the same way to me when I compare one to the Nissan that I drive. The Tabla does slightly out-perform the S/PDIF Mk3, and as we all should know by now, that last bit of improvement in any hi-fi equipment often comes with a sobering price increase. Both Muto DAC's would be on my favourites list, and also performed very well when fed from a couple of CDP's, but it's with a good computer source such as the Tabla, that they sound their best.

[Human Tabla and Muto showing size against a CD.]

If there is one negative about the Tabla/Muto, it would be the tiny switches on the rear. If you are placing these items on anything but the top tier of your equipment rack, you will find it very fiddly to reach these switches when you have to turn them on and off at each session. The same goes for having to plug and unplug the charger lead. I like the uncluttered look of the front-plates but would happily exchange that to have the on/off switch located there instead of at the rear. As regards the batteries and charging, I had no problems at all during the time that I was auditioning the Tabla/Muto. I left the Muto connected to its charger all the time and simply turned it on and off as required. The Muto-X did need to have the charger lead unplugged for listening sessions, and did of course need to have it reconnected afterwards. Photographing these little beasts with their mirror-finish panels was no fun either, and my pictures don't really do them full justice!

I also feel it responsible of me to write something more about the 'battery sound' of not just the Tabla/Muto, bit other items of hi-fi such as the JKDAC32 and SPDIF Mk3 from John Kenny. There's no doubt in my mind that one of the biggest problems that we have with getting the best sound from our hi-fi systems is the quality (or lack of it) of our mains power supply. I believe that its quality is inferior to what we had (at least in the UK) 40 or 50 years ago, and that it is going to get worse. For instance, quite understandably, LED street lighting is going to become the norm. It's environmentally, and economically superior to the existing types of lighting. However, that many LEDs are going to have a negative effect on the mains. Using the mains for data transmission will also pollute it, just as the ever increasing number of switching power supplies do. So the advantages of batteries (and any other off-grid supply) are becoming increasingly attractive to those of us who value the quality of our music reproduction. And I guess that is a large part of why Human Audio, and John Kenny (to name but two) manufacturers have chosen to use batteries in their equipment.

I have already alluded to the fact that the LiFeP04 batteries used in the Tabla/Muto sound a whole lot better than the SLA type, but that ultimately they appear to lack a little 'oomph' when compared to using a mains supply. As it happens, as I write up this review, I have another item for review where I am able to use different types of power supply with it. Using that with a battery supply (niMH AA batteries) and a very high quality mains supply, has brought home to me difference that the power supply makes. Which is better? To be honest, neither is, they both have their strong points and their weaknesses. The battery supply lacks the 'oomph' and the mains supply lacks the purity of sound that I hear from the battery supply. How I wish we could have the best of both combined into one supply!

So, coming back to the Tabla/Muto, I will stick to my original statement that I could (make that would) live with the sound, and get used to the slight lack of 'oomph', because I feel that the benefits of the battery supply outweigh that. But it is definitely personal taste, and also a lot down to which genre of music you favour, and to some degree, the partnering equipment. I have corresponded with one or two people who feel that the battery supply does sound a bit too soft and lacking in 'oomph' for them, and they prefer to stick with mains powered equipment. (I should state that they had not actually heard the Tabla/Muto)

The main question when buying a Muto would be Jfet, or transformer output, and that will really be down to personal preference, and the difference in their prices. The Tabla is easier to recommend - simply the best USB converter that I have heard to date! Perhaps the best thing that I can say about the Tabla/Muto is that on quite a few occasions, I thought some of my older albums like Pink Floyd's 'Dark Side of the Moon', and Al Stewart's 'Bedsitter Images' to name just two, sounded awfully close to how they used to sound on vinyl. After all my time reviewing, returning these items to the supplier was the first time that I truly wished that I could afford to buy a review item!