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New HLLY SMK-III Digital Audio Decoder

post #1 of 138
Thread Starter 

My first experience with the HLLY brand was as a result of skylab loaning me the HLLY DMK-IV as documented on: http://www.head-fi.org/forum/thread/468719/review-hlly-dmk-iv-dac-headphone-amp-pre-amp I hope to reciprocate and send this unit in to Rob (skylab) in about a month so he can post his impressions.


Today I received a package and it was a pleasant surprise, it not only included the latest DAC from HLLY the SMK-III but also their AMK-II Pre-Amp. This thread will concentrate on the SMK-III a 24-96 digital to analog converter. The unit is much larger measuring 8-5/8" wide by 11-1/4" deep by 3-1/2" high. The unit accepts digital information via:


1. Coaxial

2. USB

3. Optical

4. AES


The SMK-III outputs analog signal via a pair of RCA's and also via balanced XLR3 outs. The front panel brushed aluminum with black letters and led's in three colors: green for the DAC, yellow for the invert, and red for the headphone amp. The unit is currently being fed via the USB input from an iMac/iTunes using lossless files and the output is via the internal headphone out to a Sennheiser HD580. I hope to start feeding it via an optical input after about 100 hours, then after logging 100 hours using the optical input I will log about 20-30 hours using the coaxial input. I plan on feeding an external headphone amp using the unbalanced analog out for about 100 hours out of the 230 total burn-in (arbitrary number). At the end I plan to do a side by side of the two DAC sections (SMK-III versus DMK-IV) using a Graham Slee SRGII headphone amp and an RS-1, HD580, and a MarkL modded Denon.


Initial impressions are good in that it allows the user to know if he/she can leave with the equipments sound. Although I believe in burn-in I also believe that no amount of burn-in will turn a piece of gear you do not like into one you find superb. I should mention that I have been using the older HLLY DMK-IV for months in my office and have gotten to know its sound quite well. The DMK-IV's DAC is quite nice but the headphone amp section could use some improvements in clarity and detail. The initial impression of the SMK-III is that its headphone out has been improved and significantly, the instruments are much easier to place, clarity/detail has been improved, as well as note start/finish are much easier to hear. But enough of initial impressions, I will let the unit cook and will then post more on it. I will add this unit's top stays cool to the touch, while the DMK-IV gets warm.


For now I leave you with the following pictures, the last one was taken to show that even the large 1/4" Furutech plug fits without any problems.









post #2 of 138
Thread Starter 

Today I was successful in sending 24/96 Wave files and be recognized by the HLLY SMK-III as a 96K file. I took me a while to realize the iMac output is normally set at 16/44.1 and I had to go to the Audio MIDI Setup inside the Utilities folder to allow the computer to send 24/96 out via the USB. If someone knows of a simpler way please let me know. So far the unit has about 12 hours of use and although early in the burn-in process I can describe the sound as smooth.


I have sent David a PM indicating the unit suffered minor damaged in transit. Basically the end of the box was partially crushed in causing the volume pot to be pushed in a bit. I was able to re-set the volume knob so now it does not drag but at extreme volume levels there is an slight channel imbalance with the right channel sounding a bit louder. However, even though I listen at very low levels the imbalance is at a level not even I would listen at being waaay too low. This observation is when using a Senn HD580 can. The only other thing I can think for now is the misspelling of the word "Decoder" for "Decooer", since this one of the very first units I am sure the error can be corrected.


I shall continue burning the unit and will report back later. BTW, enclosed is a picture of the front faceplate showing it is seeing a 96K file via USB. Cheers.



post #3 of 138

Looking forward to more impressions

post #4 of 138
Thread Starter 

The unit is at the 50 hour mark of burn-in as of 9:00am EST today August 28th. Currently I am feeding an external amp, Musical Fidelity X-Can fully modded by PinkFloyd and for cans I am using a highly modded Grado SR80.  The sound is indeed smooth with the external amp or the internal SMK-III headphone amp. I really do not wish to say much to allow the unit to go through the 230 hours (arbitrary number I chose) of burn-in  but it truly is hard to stay quiet. This unit at the MSRP of $300 will be IMO very hard to beat, the sound is so much better than DMK-IV as to not be a fair comparison.


I went to the previous thread and "borrowed" some of the technical information posted by David Gao and I have posted it below, the intent is to keep as much of the information in one place. I have also "borrowed" some of the pictures posted by David Gao. The last picture is of the rig as I am using now, BTW the source continues to be an iMac/iTunes lossless files via USB to the SMK-III.





    The price is set to USD 300 including shipping to USA & West Europe!

It use Te7022L USB chip and support 24bit/96K for USB!


Here is the Parameters:


Frequency response:20Hz~20KHz(+/-1dB)
Output amplitude:RCA---2.0Vrms
S/N: >115dB
Channel separation:>110dB
Dynamic Range:>100dB(16bit)   >125dB(24bit)
THD+N: <0.0012%(16bit)   <0.0008%(24bit)
USB: USB2.0、Sampling frequency:32~96KHz  Support ASIO
Coaxial IN:Input Sensitivity:400mVp-p
Sampling frequency:32~96KHz
Coaxial OUT: 0.5Vp-p 75OHMS
Power consumption: <15W




 1.  the volume is analog, not digital!

 2.  Yes, it is class AB buffer circuit for the headphone amp!

 3.  Yes, headphone amplifer DC-Coupled!

 4.  The LEDs at the front just show the actual sample rate!











post #5 of 138

looks like a very nice unit.  I still like my DMK-IV, it has a permanent home next to the bed.  HLLY does packs their items with a ton of nice features.

post #6 of 138
Thread Starter 

Today marks the 6th day since I received the SMK-III, it currently has about 120 hours of burn-in. This is about the half way point of the initial plan I arbitrarily established as part of its sound evaluation. As of today all the digital signal has been fed via USB and the SMK-III has been used both as DAC feeding a Musical Fidelity X-Can modded by PinkFloyd or as a single unit (amp/dac combo). The latest headphone I have used is an AKG K501 with a V3 APureSound 10' re-cable terminated in a Furutech FP-704 1/4" plug. As you can imagine the K501 has required more juice than either of the RS-1 or HD-580 I previously used.


Overall I will say the sound is very consistent amongst such a varied set of cans. This has surprised me since as a norm most amps exhibit a preference for a particular headphone type, this has not been the case so far but it could still change (burn-in). How would I describe what I hear? Early in the process I wrote "smooth" and till now I feel this word strongly describes what I hear. To me this is a good thing because too many amps/dacs exhibit peaks in the frequency range that some (myself included) may find objectionable. So far the presentation is very even and it allows for a very enjoyable morning or evening spent listening to your favorite jazz ensemble or string quartet.


As I write this impression I am listening to John Coltrane's Blue train by Blue Note. Listening to the hi-hat opening and closing is an interesting experience when I remember this unit retails for $300. The level of micro detail and clarity of the saxophone playing concurrently is very engaging and enjoyable. This level of performance is not what I would expect of units in this price range. Perhaps the industry and technology have caught up and it now allows companies to offer an unit like the SMK-III with such a high value.


Would I change anything? Provided we realize the burn-in is not over I would probably request a higher grade of a potentiometer and corresponding knob. This is very nitpicking but so is this hobby. Next, I would ask for a bit more bass impact in the headphone amp section not the DAC section. This last is mostly for those who would be using cans like the K501 which have a beautiful mid-range but not lots of bass. If you are using something along the lines of the Denon or Grado it would not IMO be needed. Note: I just remember I can roll op-amps! Oh boy this could be a lot of fun.


I hope to wrap this up in about ten days or so. I may choose to take a bit more time not due to burn-in itself but for my ears to continue getting used to the sound out of the SMK-III. After wards I plan on sending the unit to Rob for his comments, by that time I will probably replace the volume pot with an stock replacement to correct the hit the unit received while in transit from China to Florida.

Edited by mrarroyo - 8/31/10 at 5:51pm
post #7 of 138

Opamp rolling is always a plus!

post #8 of 138

Great read, Miguel.


I am still liking my T-Amp 20 with the K1000 I have currently. Sound is fantastic for such a cheap little unit. 

post #9 of 138
Thread Starter 

Mad Max ===> You are correct!


stang ===> It looks like I have a T-Amp 20 on the way!  It will be used to power a K1000 and an Stax Lambda Pro via an SRD7/Pro energizer box.  Of course the impressions would go on a different thread. Cheers and thanks.

post #10 of 138



Having a 110/220 volt toggle switch on the back is NOT a good idea.


If you live in a country with 220 one accidental nudge will kill it.


Why not learn from other manufacturers and have a recessed switch or behind a cover.

post #11 of 138
Thread Starter 
Originally Posted by ford2 View Post



Having a 110/220 volt toggle switch on the back is NOT a good idea.


If you live in a country with 220 one accidental nudge will kill it.


Why not learn from other manufacturers and have a recessed switch or behind a cover.

Hi, the toggle switch is not to switch voltages. Instead it is the ON/OFF switch, I hope in the next production run this labeling issue is improved upon.

post #12 of 138
Originally Posted by mrarroyo View Post

Hi, the toggle switch is not to switch voltages. Instead it is the ON/OFF switch, I hope in the next production run this labeling issue is improved upon.

Take a lot to beat that.

post #13 of 138
Thread Starter 

For the last 48 hours I have been using an optical cable made by Sys. Concept Inc. to send the music (16/44.1) from the iMac to the HLLY SMK-III. At first I thought the sound was the same as if the SMK-III was fed via the USB, at about the 30 hour mark I started to hear a bit more detail and the sound was clearer. The difference is not a night and day, instead it is to my ears a subtle one.


I then started sending 24/96 files, the differences became more pronounce although I still would not consider them night/day differences. Instead the sound is a bit more open, with more air, and easier to distinguish the notes and place the instruments.


Over the next week I will just try to enjoy the unit and not try to compare tracks. I truly believe the beauty of the SMK-III lies in its "not being there" sound, this at a very low cost to the end user. I hope others enjoy it as much as I have. I want to thank David for making this unit available to me.

Edited by mrarroyo - 9/3/10 at 4:41pm
post #14 of 138

How's the built-in headamp?

post #15 of 138

Is it possible to use the volume knob on this DAC to fine-tune the overall (master)volume when used in combination with a headphone amp?

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