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Audio 2018

February 19, 2018

It’s been a long time since I did an item about my audio hobby. “Audio” means machines that make music more enjoyable.

February 2, 2014: Audio 2014

July 5, 2015: Audio 2015

If you remember, I used to have a rather ambitious (actually, very ambitious) DIY horn setup, based around some wideband horns from the 1930s, used in the 115-6000hz range. I sold that off, and went back to headphones.

I still have the headphones. Headphone audio has become much more popular in the last 15 years or so, and for good reason. It is an easy way to achieve a very high level of sound quality, without an excessive budget, bothering the neighbors, or making a mess of your interior decoration. An ambitious speakers and amps combo is really a considerable challenge, and I would say that almost nothing today, at any price, approaches what I would do if I were to take that challenge up again. (I would get some Danley SH50s, and tri-amp them with a digital FIR crossover, combined with six channels of quality DACs, plus six channels of quality amplification, plus subwoofers.)

So, headphones. I still have the Sennheiser HD600 (about $300), which is like the Mercedes SL300 “Gullwing” of headphones. Old, but classic. Very classic. I also have some Audeze LCD-2s and Etymotic ER-4P in-ear-monitors (IEMs).

This is driven with a first-generation Metrum Octave DAC, going direct into some 600-ohm autoformer volume controls (the “$200 autoformer volume control”) from Dave Slagle at Intact Audio. As I explained earlier, the Metrum Octave is an R2R ladder-type DAC, without an output stage. The output of the DAC chips goes direct into the transformers, and then direct into your headphones with no other active stages.


Yes, you can do that. And, it seems that I am not the only one doing this. I have heard that others are doing so, using the TotalDAC units. But, it is a very small crew indeed.

This sounds awesome. It is so awesome that it makes any more searching for electronics somewhat moot. Yes, there are better DACs now, including newer models from Metrum, but I don’t feel a need to upgrade. I tried this combo with my 01A-71A SET headphone amp, and also an amp based on the SK170 jfet–both of which are much better than some commercial headphone amps I’ve had around here–and found much what I expected to find: the output sounds like you would predict, modified by passing through some very good electronics. All in all, it was a modest step down. I did not find that using amplification gave better dynamics, or any other enhancement of that sort. The SK170 amp was somewhat sharper and grainier than the autoformers alone, but it “sang” like a really good solid-state solution should. The 01A-71A combo was smooth and sweet, with some coloration and loss of detail. The 71A amp was better.

Sometimes Less Is More, especially in audio, where Keep It Simple Stupid (KISS) usually works. This is about as less as you can get. Nevertheless, this solution requires higher-efficiency headphones. I would suggest 95db/mW or better. And, it is often wide open or attenuated by just a couple clicks (at 3db per click). Theoretically, I could use amplification on recordings that had a low level (some classical), but this is basically never necessary. More commonly, if I want to “turn it up” beyond the highest click, I just use the Etymotic IEMs, which are still more efficient.

Etymotic’s ER-4P is here, for $299. Etymotic also offers the HF5 at $99 and the MC5 at $65, which might be almost as good.

The output of the Metrum is max 2V rms at 100R output impedance. This translates into 10mW into the 300-ohm load of the HD600 headphones. At 97db/mW, you get around a 107db peak on the HD600s, which is twenty db above an average listening level of 87db at the ear, which is certainly loud enough. You shouldn’t go louder, especially on headphones.

The Intact Audio autoformers are a DIY solution. Fortunately, there seems to be a readymade version of the same thing, and it is cheap, too. This $150 item appears to do the same thing (although I haven’t verified that):


You can search for either the 1G Metrum Octave, or the 2G which incorporates a USB convertor in one box, on the used market. (I would go for the 2G today.) Both can be found used for less than $800. Metrum’s latest offerings (all of which, I believe, maintain the original direct-from-chip-to-output topology) are here:


The whole setup is rather clumsy, as it also includes a MacBook Air as a server running Audirvana, and a Peachtree Audio X1 USB/SPDIF convertor. Boxes all over the desktop. As an alternative, I also have a Fiio X7  portable music player (recently available for about $300), which is rather a nice unit based on the Sabre 9018 chip. This is used with the stock “AM1” buffer and the Etymotic IEMs. The X7 is not nearly as good as the Metrum/autoformer setup, but it is pretty good nevertheless, and is also very portable. If you wanted to get great sound for under $400, which you can also use with wifi streaming services, the X7/Etymotic HF5 combo is a winner. For a solution that you can use with your smartphone, I would go for the Chord Mojo (about $500). You can keep up on new product offerings at head-fi.org. Among portable solutions, I suggest that you get either the X7 or Chord, and the Etymotics, and listen to them for a year. Then, if you want to (better if you don’t), try some other solutions and decide for yourself if you like them better. You might not. Don’t take anybody else’s opinion seriously. Just listen and decide for yourself. Hardly anyone today shares my fondness for the HD600 headphones. They much prefer the HD800, from the same company, at four times the price. Because, if it is from the same company, and four times the price, it must be better, right? But, I have tried them both, and prefer the HD600. So that’s the way it is, for me.

All of these things might be available on the used market. I would try head-fi.org’s For Sale forum, or eBay.

Of course, you need to also use good music to begin with. Avoid all compressed streaming services. Tidal offers an uncompressed 16/44 (same as CD) option. Also, look into places like hdtracks.com for 24/96 and higher “high resolution” files. If you use a streaming service like Tidal, also look into better-quality interface software. Amarra SQ offers a solution especially for Tidal, and it is not expensive.

I don’t really bother with these things too much anymore, because I know how hard it would be to beat what I have, at any reasonable price. But, I am glad I walked the path, because I also know how much better the good stuff is. If you are starting this process, either of these solutions should give you an idea of what is possible, and enable you to enjoy lots of good music.